CVE-2026-27858 (GCVE-0-2026-27858)

Vulnerability from cvelistv5 – Published: 2026-03-27 08:10 – Updated: 2026-06-30 03:19
VLAI
Summary
Attacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount of memory. Attacker can force managesieve-login to be unavailable by repeatedly crashing the process. Protect access to managesieve protocol, or install fixed version. No publicly available exploits are known.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
  • CWE-400 - Uncontrolled Resource Consumption
  • CWE-770 - Allocation of Resources Without Limits or Throttling
Assigner
OX
References
URL Tags
https://documentation.open-xchange.com/dovecot/se… vendor-advisory
https://access.redhat.com/security/cve/CVE-2026-27858 vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2452175 issue-trackingx_refsource_REDHAT
https://security.access.redhat.com/data/csaf/v2/v… x_sadp-csaf-vex
https://access.redhat.com/errata/RHSA-2026:26564 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:17602 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:13498 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:19149 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:13830 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:19455 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:19453 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:18053 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:17630 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:17628 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:17625 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:17626 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:13857 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:19364 vendor-advisoryx_refsource_REDHAT
Impacted products
Vendor Product Version
Open-Xchange GmbH OX Dovecot Pro Affected: 0 , ≤ 2.3.0 (semver)
Affected: 0 , ≤ 3.1.0 (semver)
Affected: 0 , ≤ 2.4.0 (semver)
Create a notification for this product.
Red Hat Red Hat Enterprise Linux Server (v. 7 ELS)     cpe:/o:redhat:rhel_els:7
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux Server Optional (v. 7 ELS)     cpe:/o:redhat:rhel_els:7
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux AppStream EUS (v. 10.0)     cpe:/o:redhat:enterprise_linux_eus:10.0
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux AppStream (v. 10)     cpe:/o:redhat:enterprise_linux:10.1
    cpe:/o:redhat:enterprise_linux:10.2
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux AppStream (v. 8)     cpe:/a:redhat:enterprise_linux:8::appstream
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux AppStream AUS (v.8.4)     cpe:/a:redhat:rhel_aus:8.4::appstream
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)     cpe:/a:redhat:rhel_eus_long_life:8.4::appstream
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux AppStream AUS (v.8.6)     cpe:/a:redhat:rhel_aus:8.6::appstream
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux AppStream E4S (v.8.6)     cpe:/a:redhat:rhel_e4s:8.6::appstream
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux AppStream TUS (v.8.6)     cpe:/a:redhat:rhel_tus:8.6::appstream
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux AppStream E4S (v.8.8)     cpe:/a:redhat:rhel_e4s:8.8::appstream
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux AppStream TUS (v.8.8)     cpe:/a:redhat:rhel_tus:8.8::appstream
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux AppStream E4S (v.9.0)     cpe:/a:redhat:rhel_e4s:9.0::appstream
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux AppStream E4S (v.9.2)     cpe:/a:redhat:rhel_e4s:9.2::appstream
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux AppStream EUS (v.9.4)     cpe:/a:redhat:rhel_eus:9.4::appstream
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux AppStream EUS (v.9.6)     cpe:/a:redhat:rhel_eus:9.6::appstream
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux AppStream (v. 9)     cpe:/a:redhat:enterprise_linux:9::appstream
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)     cpe:/o:redhat:enterprise_linux_eus:10.0
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)     cpe:/o:redhat:enterprise_linux:10.1
    cpe:/o:redhat:enterprise_linux:10.2
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux CRB (v. 8)     cpe:/a:redhat:enterprise_linux:8::crb
 Create a notification for this product.
Red Hat Red Hat CodeReady Linux Builder EUS (v.9.4)     cpe:/a:redhat:rhel_eus:9.4::crb
 Create a notification for this product.
Red Hat Red Hat CodeReady Linux Builder EUS (v.9.6)     cpe:/a:redhat:rhel_eus:9.6::crb
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)     cpe:/a:redhat:enterprise_linux:9::crb
 Create a notification for this product.
Red Hat Red Hat Enterprise Linux 6     cpe:/o:redhat:enterprise_linux:6
 Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-27858",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-27T12:36:26.526829Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-27T12:37:09.762Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      },
      {
        "affected": [
          {
            "cpes": [
              "cpe:/o:redhat:rhel_els:7"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux Server (v. 7 ELS)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/o:redhat:rhel_els:7"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux Server Optional (v. 7 ELS)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/o:redhat:enterprise_linux_eus:10.0"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux AppStream EUS (v. 10.0)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/o:redhat:enterprise_linux:10.1",
              "cpe:/o:redhat:enterprise_linux:10.2"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux AppStream (v. 10)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:enterprise_linux:8::appstream"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux AppStream (v. 8)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:rhel_aus:8.4::appstream"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux AppStream AUS (v.8.4)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:rhel_eus_long_life:8.4::appstream"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:rhel_aus:8.6::appstream"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux AppStream AUS (v.8.6)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:rhel_e4s:8.6::appstream"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux AppStream E4S (v.8.6)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:rhel_tus:8.6::appstream"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux AppStream TUS (v.8.6)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:rhel_e4s:8.8::appstream"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux AppStream E4S (v.8.8)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:rhel_tus:8.8::appstream"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux AppStream TUS (v.8.8)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:rhel_e4s:9.0::appstream"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux AppStream E4S (v.9.0)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:rhel_e4s:9.2::appstream"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux AppStream E4S (v.9.2)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:rhel_eus:9.4::appstream"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux AppStream EUS (v.9.4)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:rhel_eus:9.6::appstream"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux AppStream EUS (v.9.6)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:enterprise_linux:9::appstream"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux AppStream (v. 9)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/o:redhat:enterprise_linux_eus:10.0"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/o:redhat:enterprise_linux:10.1",
              "cpe:/o:redhat:enterprise_linux:10.2"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:enterprise_linux:8::crb"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux CRB (v. 8)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:rhel_eus:9.4::crb"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat CodeReady Linux Builder EUS (v.9.4)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:rhel_eus:9.6::crb"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat CodeReady Linux Builder EUS (v.9.6)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/a:redhat:enterprise_linux:9::crb"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)",
            "vendor": "Red Hat"
          },
          {
            "cpes": [
              "cpe:/o:redhat:enterprise_linux:6"
            ],
            "defaultStatus": "affected",
            "product": "Red Hat Enterprise Linux 6",
            "vendor": "Red Hat"
          }
        ],
        "datePublic": "2026-03-27T08:10:21.424Z",
        "descriptions": [
          {
            "lang": "en",
            "value": "A flaw was found in dovecot. An unauthenticated and remote attacker can send a crafted message that causes managesieve to allocate an excessive amount of memory, forcing managesieve-login to be unavailable by repeatedly crashing the process, resulting in a denial of service."
          }
        ],
        "metrics": [
          {
            "other": {
              "content": {
                "namespace": "https://access.redhat.com/security/updates/classification/",
                "value": "Important"
              },
              "type": "Red Hat severity rating"
            }
          },
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
              "availabilityImpact": "HIGH",
              "baseScore": 7.5,
              "baseSeverity": "HIGH",
              "confidentialityImpact": "NONE",
              "integrityImpact": "NONE",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
              "version": "3.1"
            },
            "format": "CVSS"
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-770",
                "description": "Allocation of Resources Without Limits or Throttling",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-06-30T03:19:54.474Z",
          "orgId": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
          "shortName": "redhat-SADP"
        },
        "references": [
          {
            "tags": [
              "vdb-entry",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/security/cve/CVE-2026-27858"
          },
          {
            "name": "RHBZ#2452175",
            "tags": [
              "issue-tracking",
              "x_refsource_REDHAT"
            ],
            "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2452175"
          },
          {
            "tags": [
              "x_sadp-csaf-vex"
            ],
            "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27858.json"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:26564"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:17602"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:13498"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:19149"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:13830"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:19455"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:19453"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:18053"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:17630"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:17628"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:17625"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:17626"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:13857"
          },
          {
            "tags": [
              "vendor-advisory",
              "x_refsource_REDHAT"
            ],
            "url": "https://access.redhat.com/errata/RHSA-2026:19364"
          }
        ],
        "solutions": [
          {
            "lang": "en",
            "value": "RHSA-2026:26564: Red Hat Enterprise Linux Server (v. 7 ELS), Red Hat Enterprise Linux Server Optional (v. 7 ELS)"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:17602: Red Hat Enterprise Linux AppStream EUS (v. 10.0), Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:13498: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:19149: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:13830: Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux CRB (v. 8)"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:19455: Red Hat Enterprise Linux AppStream AUS (v.8.4), Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:19453: Red Hat Enterprise Linux AppStream AUS (v.8.6), Red Hat Enterprise Linux AppStream E4S (v.8.6), Red Hat Enterprise Linux AppStream TUS (v.8.6)"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:18053: Red Hat Enterprise Linux AppStream E4S (v.8.8), Red Hat Enterprise Linux AppStream TUS (v.8.8)"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:17630: Red Hat Enterprise Linux AppStream E4S (v.9.0)"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:17628: Red Hat Enterprise Linux AppStream E4S (v.9.2)"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:17625: Red Hat CodeReady Linux Builder EUS (v.9.4), Red Hat Enterprise Linux AppStream EUS (v.9.4)"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:17626: Red Hat CodeReady Linux Builder EUS (v.9.6), Red Hat Enterprise Linux AppStream EUS (v.9.6)"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:13857: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)"
          },
          {
            "lang": "en",
            "value": "RHSA-2026:19364: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)"
          }
        ],
        "timeline": [
          {
            "lang": "en",
            "time": "2026-03-27T09:01:45.192Z",
            "value": "Reported to Red Hat."
          },
          {
            "lang": "en",
            "time": "2026-03-27T08:10:21.424Z",
            "value": "Made public."
          }
        ],
        "title": "dovecot: denial of service via crafted message before authentication",
        "workarounds": [
          {
            "lang": "en",
            "value": "To mitigate this vulnerability, protect access to the managesieve protocol by configuring firewall rules to restrict access to the managesieve port and only allow connections from trusted IP addresses or networks."
          }
        ],
        "x_adpType": "supplier",
        "x_generator": {
          "engine": "sadp-cli 1.0.0"
        }
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "modules": [
            "core"
          ],
          "product": "OX Dovecot Pro",
          "vendor": "Open-Xchange GmbH",
          "versions": [
            {
              "lessThanOrEqual": "2.3.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "3.1.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "2.4.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Attacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount of memory.\r\n Attacker can force managesieve-login to be unavailable by repeatedly crashing the process. Protect access to managesieve protocol, or install fixed version. No publicly available exploits are known."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-400",
              "description": "Uncontrolled Resource Consumption",
              "lang": "en",
              "type": "cwe"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-27T12:33:31.126Z",
        "orgId": "8ce71d90-2354-404b-a86e-bec2cc4e6981",
        "shortName": "OX"
      },
      "references": [
        {
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json"
        }
      ],
      "source": {
        "defect": "DOV-8818",
        "discovery": "EXTERNAL"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "8ce71d90-2354-404b-a86e-bec2cc4e6981",
    "assignerShortName": "OX",
    "cveId": "CVE-2026-27858",
    "datePublished": "2026-03-27T08:10:21.424Z",
    "dateReserved": "2026-02-24T08:46:09.374Z",
    "dateUpdated": "2026-06-30T03:19:54.474Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-27858",
      "date": "2026-06-29",
      "epss": "0.00456",
      "percentile": "0.36315"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-27858\",\"sourceIdentifier\":\"security@open-xchange.com\",\"published\":\"2026-03-27T09:16:20.073\",\"lastModified\":\"2026-06-30T03:17:58.790\",\"vulnStatus\":\"Modified\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Attacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount of memory.\\r\\n Attacker can force managesieve-login to be unavailable by repeatedly crashing the process. Protect access to managesieve protocol, or install fixed version. No publicly available exploits are known.\"}],\"affected\":[{\"source\":\"security@open-xchange.com\",\"affectedData\":[{\"vendor\":\"Open-Xchange GmbH\",\"product\":\"OX Dovecot Pro\",\"defaultStatus\":\"unaffected\",\"modules\":[\"core\"],\"versions\":[{\"version\":\"0\",\"lessThanOrEqual\":\"2.3.0\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThanOrEqual\":\"3.1.0\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThanOrEqual\":\"2.4.0\",\"versionType\":\"semver\",\"status\":\"affected\"}]}]},{\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\",\"affectedData\":[{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux Server (v. 7 ELS)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/o:redhat:rhel_els:7\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux Server Optional (v. 7 ELS)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/o:redhat:rhel_els:7\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux AppStream EUS (v. 10.0)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/o:redhat:enterprise_linux_eus:10.0\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux AppStream (v. 10)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/o:redhat:enterprise_linux:10.1\",\"cpe:/o:redhat:enterprise_linux:10.2\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux AppStream (v. 8)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:enterprise_linux:8::appstream\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux AppStream AUS (v.8.4)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:rhel_aus:8.4::appstream\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:rhel_eus_long_life:8.4::appstream\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux AppStream AUS (v.8.6)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:rhel_aus:8.6::appstream\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux AppStream E4S (v.8.6)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:rhel_e4s:8.6::appstream\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux AppStream TUS (v.8.6)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:rhel_tus:8.6::appstream\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux AppStream E4S (v.8.8)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:rhel_e4s:8.8::appstream\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux AppStream TUS (v.8.8)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:rhel_tus:8.8::appstream\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux AppStream E4S (v.9.0)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:rhel_e4s:9.0::appstream\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux AppStream E4S (v.9.2)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:rhel_e4s:9.2::appstream\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux AppStream EUS (v.9.4)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:rhel_eus:9.4::appstream\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux AppStream EUS (v.9.6)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:rhel_eus:9.6::appstream\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux AppStream (v. 9)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:enterprise_linux:9::appstream\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/o:redhat:enterprise_linux_eus:10.0\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/o:redhat:enterprise_linux:10.1\",\"cpe:/o:redhat:enterprise_linux:10.2\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux CRB (v. 8)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:enterprise_linux:8::crb\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat CodeReady Linux Builder EUS (v.9.4)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:rhel_eus:9.4::crb\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat CodeReady Linux Builder EUS (v.9.6)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:rhel_eus:9.6::crb\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/a:redhat:enterprise_linux:9::crb\"]},{\"vendor\":\"Red Hat\",\"product\":\"Red Hat Enterprise Linux 6\",\"defaultStatus\":\"affected\",\"cpes\":[\"cpe:/o:redhat:enterprise_linux:6\"]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security@open-xchange.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":7.5,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":3.6},{\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":7.5,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":3.6}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2026-03-27T12:36:26.526829Z\",\"id\":\"CVE-2026-27858\",\"options\":[{\"exploitation\":\"none\"},{\"automatable\":\"yes\"},{\"technicalImpact\":\"partial\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"security@open-xchange.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-400\"}]},{\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-770\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:dovecot:dovecot:*:*:*:*:*:*:*:*\",\"versionEndExcluding\":\"2.4.3\",\"matchCriteriaId\":\"BE209329-C5EA-4EE7-A23E-CD2EC061A9A4\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*\",\"versionEndExcluding\":\"2.3.22.1\",\"matchCriteriaId\":\"5CF82590-D98A-4E06-AC8C-6CC3506ED923\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*\",\"versionStartIncluding\":\"3.0.0\",\"versionEndExcluding\":\"3.0.5\",\"matchCriteriaId\":\"8476287B-40B2-4533-A3AB-B880516C0B5C\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*\",\"versionStartIncluding\":\"3.1.0\",\"versionEndExcluding\":\"3.1.4\",\"matchCriteriaId\":\"11CA35AA-72CB-4614-A064-8A90F65D8A71\"}]}]}],\"references\":[{\"url\":\"https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json\",\"source\":\"security@open-xchange.com\",\"tags\":[\"Vendor Advisory\"]},{\"url\":\"https://access.redhat.com/errata/RHSA-2026:13498\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://access.redhat.com/errata/RHSA-2026:13830\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://access.redhat.com/errata/RHSA-2026:13857\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://access.redhat.com/errata/RHSA-2026:17602\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://access.redhat.com/errata/RHSA-2026:17625\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://access.redhat.com/errata/RHSA-2026:17626\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://access.redhat.com/errata/RHSA-2026:17628\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://access.redhat.com/errata/RHSA-2026:17630\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://access.redhat.com/errata/RHSA-2026:18053\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://access.redhat.com/errata/RHSA-2026:19149\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://access.redhat.com/errata/RHSA-2026:19364\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://access.redhat.com/errata/RHSA-2026:19453\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://access.redhat.com/errata/RHSA-2026:19455\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://access.redhat.com/errata/RHSA-2026:26564\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://access.redhat.com/security/cve/CVE-2026-27858\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://bugzilla.redhat.com/show_bug.cgi?id=2452175\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"},{\"url\":\"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27858.json\",\"source\":\"0b0ca135-0b70-47e7-9f44-1890c2a1c46c\"}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-27858\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-03-27T12:36:26.526829Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-03-27T12:37:04.235Z\"}}], \"cna\": {\"source\": {\"defect\": \"DOV-8818\", \"discovery\": \"EXTERNAL\"}, \"metrics\": [{\"format\": \"CVSS\", \"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 7.5, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"NONE\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}], \"affected\": [{\"vendor\": \"Open-Xchange GmbH\", \"modules\": [\"core\"], \"product\": \"OX Dovecot Pro\", \"versions\": [{\"status\": \"affected\", \"version\": \"0\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"2.3.0\"}, {\"status\": \"affected\", \"version\": \"0\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"3.1.0\"}, {\"status\": \"affected\", \"version\": \"0\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"2.4.0\"}], \"defaultStatus\": \"unaffected\"}], \"references\": [{\"url\": \"https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json\", \"tags\": [\"vendor-advisory\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"Attacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount of memory.\\r\\n Attacker can force managesieve-login to be unavailable by repeatedly crashing the process. Protect access to managesieve protocol, or install fixed version. No publicly available exploits are known.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"cwe\", \"cweId\": \"CWE-400\", \"description\": \"Uncontrolled Resource Consumption\"}]}], \"providerMetadata\": {\"orgId\": \"8ce71d90-2354-404b-a86e-bec2cc4e6981\", \"shortName\": \"OX\", \"dateUpdated\": \"2026-03-27T12:33:31.126Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-27858\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-03-27T12:37:09.762Z\", \"dateReserved\": \"2026-02-24T08:46:09.374Z\", \"assignerOrgId\": \"8ce71d90-2354-404b-a86e-bec2cc4e6981\", \"datePublished\": \"2026-03-27T08:10:21.424Z\", \"assignerShortName\": \"OX\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.