Vulnerability-Lookup

GHSA-247X-7QW8-FP98

Vulnerability from github – Published: 2026-03-25 18:31 – Updated: 2026-04-06 17:31

Summary

Mattermost doesn't rate limit login requests, allowing DoS

Details

Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to rate limit login requests which allows unauthenticated remote attackers to cause denial of service (server crash and restart) via HTTP/2 single packet attack with 100+ parallel login requests.. Mattermost Advisory ID: MMSA-2025-00566

Severity

4.3 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

Show details on source website

JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/mattermost/mattermost-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "11.4.0-rc1"
            },
            {
              "fixed": "11.4.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/mattermost/mattermost-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "11.3.0-rc1"
            },
            {
              "fixed": "11.3.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/mattermost/mattermost-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "11.2.0-rc1"
            },
            {
              "fixed": "11.2.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/mattermost/mattermost-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "10.11.0-rc1"
            },
            {
              "fixed": "10.11.12"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-26233"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-31T05:17:35Z",
    "nvd_published_at": "2026-03-25T17:16:53Z",
    "severity": "MODERATE"
  },
  "details": "Mattermost versions 11.4.x \u003c= 11.4.0, 11.3.x \u003c= 11.3.1, 11.2.x \u003c= 11.2.3, 10.11.x \u003c= 10.11.11 fail to rate limit login requests which allows unauthenticated remote attackers to cause denial of service (server crash and restart) via HTTP/2 single packet attack with 100+ parallel login requests.. Mattermost Advisory ID: MMSA-2025-00566",
  "id": "GHSA-247x-7qw8-fp98",
  "modified": "2026-04-06T17:31:46Z",
  "published": "2026-03-25T18:31:52Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-26233"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/mattermost/mattermost"
    },
    {
      "type": "WEB",
      "url": "https://mattermost.com/security-updates"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Mattermost doesn\u0027t rate limit login requests, allowing DoS"
}

CVE-2026-26233 (GCVE-0-2026-26233)

Vulnerability from cvelistv5 – Published: 2026-03-25 16:24 – Updated: 2026-03-27 14:59

Title

Denial of Service via HTTP/2 single packet attack on login endpoint

Summary

Severity

4.3 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-03-27 14:59 UTC

CWE

CWE-400 - Uncontrolled Resource Consumption

Assigner

Mattermost mitre root

References

1 reference

URL	Tags
https://mattermost.com/security-updates	vendor-advisory

Impacted products

1 product

Vendor	Product	Version
Mattermost	Mattermost	Affected: 11.4.0 , ≤ 11.4.0 (semver) Affected: 11.3.0 , ≤ 11.3.1 (semver) Affected: 11.2.0 , ≤ 11.2.3 (semver) Affected: 10.11.0 , ≤ 10.11.11 (semver) Unaffected: 11.5.0 Unaffected: 11.4.1 Unaffected: 11.3.2 Unaffected: 11.2.4 Unaffected: 10.11.12

Credits

Axel Larsson & Jakob Ristner

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-26233",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-27T14:59:40.444232Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-27T14:59:50.732Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
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          "defaultStatus": "unaffected",
          "product": "Mattermost",
          "vendor": "Mattermost",
          "versions": [
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              "lessThanOrEqual": "11.4.0",
              "status": "affected",
              "version": "11.4.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "11.3.1",
              "status": "affected",
              "version": "11.3.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "11.2.3",
              "status": "affected",
              "version": "11.2.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "10.11.11",
              "status": "affected",
              "version": "10.11.0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "11.5.0"
            },
            {
              "status": "unaffected",
              "version": "11.4.1"
            },
            {
              "status": "unaffected",
              "version": "11.3.2"
            },
            {
              "status": "unaffected",
              "version": "11.2.4"
            },
            {
              "status": "unaffected",
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            }
          ]
        }
      ],
      "credits": [
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          "type": "finder",
          "value": "Axel Larsson \u0026 Jakob Ristner"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
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        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 4.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L",
            "version": "3.1"
          },
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          "scenarios": [
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          "descriptions": [
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              "lang": "en",
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      "providerMetadata": {
        "dateUpdated": "2026-03-25T16:24:47.694Z",
        "orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee",
        "shortName": "Mattermost"
      },
      "references": [
        {
          "name": "MMSA-2025-00566",
          "tags": [
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          ],
          "url": "https://mattermost.com/security-updates"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "Update Mattermost to versions 11.5.0, 11.4.1, 11.3.2, 11.2.4, 10.11.12 or higher."
        }
      ],
      "source": {
        "advisory": "MMSA-2025-00566",
        "defect": [
          "https://mattermost.atlassian.net/browse/MM-66885"
        ],
        "discovery": "EXTERNAL"
      },
      "title": "Denial of Service via HTTP/2 single packet attack on login endpoint",
      "x_generator": {
        "engine": "cvelib 1.8.0"
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  },
  "cveMetadata": {
    "assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee",
    "assignerShortName": "Mattermost",
    "cveId": "CVE-2026-26233",
    "datePublished": "2026-03-25T16:24:47.694Z",
    "dateReserved": "2026-02-23T22:18:41.232Z",
    "dateUpdated": "2026-03-27T14:59:50.732Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.
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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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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Action not permitted

GHSA-247X-7QW8-FP98

CVE-2026-26233 (GCVE-0-2026-26233)

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