CVE-2026-104658 (GCVE-0-2026-104658)

Vulnerability from cvelistv5 – Published: 2026-10-08 10:52 – Updated: 2026-10-08 17:35
VLAI
Title
Reliance on Untrusted Inputs in a Security Decision in hMailServer
Summary
The Linux live-update apply helper (hmailserver-update) of Progressive Robot hMailServer 6.3.4 and 6.3.5 runs as root on a request file written by the unprivileged hmailserver service account, and took from that request the program used to verify an AppImage update's signature and the systemd unit to stop before reading the service account's files. An attacker who already runs code as the hmailserver service account, for example through another flaw in the mail server, can therefore have arbitrary code executed as root, on any Linux installation where the live update's path unit is active - the default for the project's .deb and .rpm packages - and on AppImage installations run under that unit.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-08 17:35 UTC
CWE
  • CWE-807 - Reliance on Untrusted Inputs in a Security Decision
Assigner
GitLab CNA under the mitre root
CNA scorecard C 75/100 over 288 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Progressive Robot Ltd hMailServer Affected: 6.3.4 , < 6.3.6 (semver)
guessed Create a notification for this product.
Credits
Found in the hMailServer project's own security review (Progressive Robot Ltd)
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-104658",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-08T17:35:35.801848Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-10-08T17:35:46.645Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "hMailServer",
          "repo": "https://gitlab.com/hmailserver/hmailserver",
          "vendor": "Progressive Robot Ltd",
          "versions": [
            {
              "lessThan": "6.3.6",
              "status": "affected",
              "version": "6.3.4",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Found in the hMailServer project\u0027s own security review (Progressive Robot Ltd)"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "The Linux live-update apply helper (hmailserver-update) of Progressive Robot hMailServer 6.3.4 and 6.3.5 runs as root on a request file written by the unprivileged hmailserver service account, and took from that request the program used to verify an AppImage update\u0027s signature and the systemd unit to stop before reading the service account\u0027s files. An attacker who already runs code as the hmailserver service account, for example through another flaw in the mail server, can therefore have arbitrary code executed as root, on any Linux installation where the live update\u0027s path unit is active - the default for the project\u0027s .deb and .rpm packages - and on AppImage installations run under that unit."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "LOCAL",
            "availabilityImpact": "HIGH",
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-807",
              "description": "CWE-807: Reliance on Untrusted Inputs in a Security Decision",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-08T10:52:45.630Z",
        "orgId": "ceab7361-8a18-47b1-92ba-4d7d25f6715a",
        "shortName": "GitLab"
      },
      "references": [
        {
          "url": "https://gitlab.com/hmailserver/hmailserver/-/work_items/58"
        },
        {
          "url": "https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "Upgrade to hMailServer 6.3.6, whose helper takes the unit and the AppImage only from its own root-owned command line, refuses an AppImage request where that names none, confirms that the server has stopped, and verifies, runs and installs only copies it made after the stop, readable by root alone until they have verified. Install 6.3.6 with the package manager (apt or dnf) rather than through the live update. An AppImage run under the path unit keeps the helper script copied to /usr/lib/hmailserver/ when its update units were installed, which the AppImage\u0027s own update does not replace: copy 6.3.6\u0027s script there and give it --image in a drop-in for hmailserver-update.service. Until then: systemctl disable --now hmailserver-update.path, which turns the apply off while the update check and download go on. Windows, builds with -DHM_LIVE_UPDATE=OFF and the container image are not affected."
        }
      ],
      "title": "Reliance on Untrusted Inputs in a Security Decision in hMailServer"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "ceab7361-8a18-47b1-92ba-4d7d25f6715a",
    "assignerShortName": "GitLab",
    "cveId": "CVE-2026-104658",
    "datePublished": "2026-10-08T10:52:45.630Z",
    "dateReserved": "2026-10-02T07:38:54.248Z",
    "dateUpdated": "2026-10-08T17:35:46.645Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "defaultStatus": "unaffected",
                "product": "hMailServer",
                "repo": "https://gitlab.com/hmailserver/hmailserver",
                "vendor": "Progressive Robot Ltd",
                "versions": [
                  {
                    "lessThan": "6.3.6",
                    "status": "affected",
                    "version": "6.3.4",
                    "versionType": "semver"
                  }
                ]
              }
            ],
            "source": "cve@gitlab.com"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "The Linux live-update apply helper (hmailserver-update) of Progressive Robot hMailServer 6.3.4 and 6.3.5 runs as root on a request file written by the unprivileged hmailserver service account, and took from that request the program used to verify an AppImage update\u0027s signature and the systemd unit to stop before reading the service account\u0027s files. An attacker who already runs code as the hmailserver service account, for example through another flaw in the mail server, can therefore have arbitrary code executed as root, on any Linux installation where the live update\u0027s path unit is active - the default for the project\u0027s .deb and .rpm packages - and on AppImage installations run under that unit."
          }
        ],
        "id": "CVE-2026-104658",
        "lastModified": "2026-10-08T21:02:43.860",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 1.8,
              "impactScore": 5.9,
              "source": "cve@gitlab.com",
              "type": "Secondary"
            }
          ],
          "ssvcV203": [
            {
              "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "ssvcData": {
                "id": "CVE-2026-104658",
                "options": [
                  {
                    "exploitation": "none"
                  },
                  {
                    "automatable": "no"
                  },
                  {
                    "technicalImpact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-08T17:35:35.801848Z",
                "version": "2.0.3"
              }
            }
          ]
        },
        "published": "2026-10-08T11:16:43.870",
        "references": [
          {
            "source": "cve@gitlab.com",
            "url": "https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6"
          },
          {
            "source": "cve@gitlab.com",
            "url": "https://gitlab.com/hmailserver/hmailserver/-/work_items/58"
          }
        ],
        "sourceIdentifier": "cve@gitlab.com",
        "vulnStatus": "Deferred",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-807"
              }
            ],
            "source": "cve@gitlab.com",
            "type": "Secondary"
          }
        ]
      }
    },
    "vulnrichment": {
      "containers": {
        "adp": [
          {
            "metrics": [
              {
                "other": {
                  "content": {
                    "id": "CVE-2026-104658",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "total"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2026-10-08T17:35:35.801848Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-10-08T17:35:42.287Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "defaultStatus": "unaffected",
              "product": "hMailServer",
              "repo": "https://gitlab.com/hmailserver/hmailserver",
              "vendor": "Progressive Robot Ltd",
              "versions": [
                {
                  "lessThan": "6.3.6",
                  "status": "affected",
                  "version": "6.3.4",
                  "versionType": "semver"
                }
              ]
            }
          ],
          "credits": [
            {
              "lang": "en",
              "type": "finder",
              "value": "Found in the hMailServer project\u0027s own security review (Progressive Robot Ltd)"
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "The Linux live-update apply helper (hmailserver-update) of Progressive Robot hMailServer 6.3.4 and 6.3.5 runs as root on a request file written by the unprivileged hmailserver service account, and took from that request the program used to verify an AppImage update\u0027s signature and the systemd unit to stop before reading the service account\u0027s files. An attacker who already runs code as the hmailserver service account, for example through another flaw in the mail server, can therefore have arbitrary code executed as root, on any Linux installation where the live update\u0027s path unit is active - the default for the project\u0027s .deb and .rpm packages - and on AppImage installations run under that unit."
            }
          ],
          "metrics": [
            {
              "cvssV3_1": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "format": "CVSS",
              "scenarios": [
                {
                  "lang": "en",
                  "value": "GENERAL"
                }
              ]
            }
          ],
          "problemTypes": [
            {
              "descriptions": [
                {
                  "cweId": "CWE-807",
                  "description": "CWE-807: Reliance on Untrusted Inputs in a Security Decision",
                  "lang": "en",
                  "type": "CWE"
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-10-08T10:52:45.630Z",
            "orgId": "ceab7361-8a18-47b1-92ba-4d7d25f6715a",
            "shortName": "GitLab"
          },
          "references": [
            {
              "url": "https://gitlab.com/hmailserver/hmailserver/-/work_items/58"
            },
            {
              "url": "https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6"
            }
          ],
          "solutions": [
            {
              "lang": "en",
              "value": "Upgrade to hMailServer 6.3.6, whose helper takes the unit and the AppImage only from its own root-owned command line, refuses an AppImage request where that names none, confirms that the server has stopped, and verifies, runs and installs only copies it made after the stop, readable by root alone until they have verified. Install 6.3.6 with the package manager (apt or dnf) rather than through the live update. An AppImage run under the path unit keeps the helper script copied to /usr/lib/hmailserver/ when its update units were installed, which the AppImage\u0027s own update does not replace: copy 6.3.6\u0027s script there and give it --image in a drop-in for hmailserver-update.service. Until then: systemctl disable --now hmailserver-update.path, which turns the apply off while the update check and download go on. Windows, builds with -DHM_LIVE_UPDATE=OFF and the container image are not affected."
            }
          ],
          "title": "Reliance on Untrusted Inputs in a Security Decision in hMailServer"
        }
      },
      "cveMetadata": {
        "assignerOrgId": "ceab7361-8a18-47b1-92ba-4d7d25f6715a",
        "assignerShortName": "GitLab",
        "cveId": "CVE-2026-104658",
        "datePublished": "2026-10-08T10:52:45.630Z",
        "dateReserved": "2026-10-02T07:38:54.248Z",
        "dateUpdated": "2026-10-08T17:35:46.645Z",
        "state": "PUBLISHED"
      },
      "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.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.