Vulnerability-Lookup

CVE-2026-27659 (GCVE-0-2026-27659)

Vulnerability from cvelistv5 – Published: 2026-03-25 16:33 – Updated: 2026-03-25 17:39

Title

CSRF vulnerability in UpdateAccessControlPolicyActiveStatus endpoint

Summary

Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to properly validate CSRF tokens in the /api/v4/access_control_policies/{policy_id}/activate endpoint, which allows an attacker to trick an admin into changing access control policy active status via a crafted request.. Mattermost Advisory ID: MMSA-2026-00578

Severity

4.6 (Medium)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-03-25 17:39 UTC

CWE

CWE-352 - Cross-Site Request Forgery (CSRF)

Assigner

Mattermost mitre root

References

1 reference

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

Impacted products

1 product

Vendor	Product	Version	CPE status
Mattermost	Mattermost	Affected: 11.2.0 , ≤ 11.2.2 (semver) Affected: 10.11.0 , ≤ 10.11.10 (semver) Affected: 11.4.0 , ≤ 11.4.0 (semver) Affected: 11.3.0 , ≤ 11.3.1 (semver) Unaffected: 11.5.0 Unaffected: 11.2.3 Unaffected: 10.11.11 Unaffected: 11.4.1 Unaffected: 11.3.2	guessed

Credits

Joshua Rogers

Show details on NVD website

JSON

To clipboard

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CERTFR-2026-AVI-0201

Vulnerability from certfr_avis - Published: 2026-02-24 - Updated: 2026-03-26

De multiples vulnérabilités ont été découvertes dans Mattermost Server. Certaines d'entre elles permettent à un attaquant de provoquer un déni de service à distance, une injection de requêtes illégitimes par rebond (CSRF) et un contournement de la politique de sécurité.

Solutions

Se référer au bulletin de sécurité de l'éditeur pour l'obtention des correctifs (cf. section Documentation).

Impacted products

Vendor	Product	Description
Mattermost	Mattermost Server	Mattermost Server versions 10.11.x antérieures à 10.11.12
Mattermost	Mattermost Server	Mattermost Server versions 11.4.x antérieures à 11.4.1
Mattermost	Mattermost Server	Mattermost Server versions 11.3.x antérieures à 11.3.2
Mattermost	Mattermost Server	Mattermost Server versions 11.2.x antérieures à 11.2.4

References

Title

Publication Time

FKIE_CVE-2026-27659

Vulnerability from fkie_nvd - Published: 2026-03-25 17:16 - Updated: 2026-06-17 10:27

Severity

4.6 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

Summary

References

	URL	Tags
	responsibledisclosure@mattermost.com	https://mattermost.com/security-updates	Vendor Advisory

Impacted products

Vendor	Product	Version
mattermost	mattermost_server	*
mattermost	mattermost_server	*
mattermost	mattermost_server	*
mattermost	mattermost_server	*

JSON

To clipboard

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    "ssvcV203": [
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        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-27659",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-03-25T17:39:20.789294Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-03-25T17:16:56.977",
  "references": [
    {
      "source": "responsibledisclosure@mattermost.com",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://mattermost.com/security-updates"
    }
  ],
  "sourceIdentifier": "responsibledisclosure@mattermost.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-352"
        }
      ],
      "source": "responsibledisclosure@mattermost.com",
      "type": "Secondary"
    }
  ]
}

GHSA-RMHW-C3XR-M3XX

Vulnerability from github – Published: 2026-03-25 18:31 – Updated: 2026-03-31 23:00

Summary

Mattermost doesn't properly validate CSRF tokens

Details

Severity

4.6 (Medium)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/mattermost/mattermost/server/v8"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "11.4.0-rc1"
            },
            {
              "fixed": "11.4.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/mattermost/mattermost/server/v8"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "11.3.0-rc1"
            },
            {
              "fixed": "11.3.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/mattermost/mattermost/server/v8"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "11.2.0-rc1"
            },
            {
              "fixed": "11.2.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c 10.11.1"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/mattermost/mattermost/server/v8"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "10.11.0-rc1"
            },
            {
              "fixed": "10.11.11"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c 8.0.0-20260217110922-b7d4a1f1f59b"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/mattermost/mattermost/server/v8"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "8.0.0-20260105080200-d27a2195068d"
            },
            {
              "fixed": "10.11.11"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-27659"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-352"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-31T23:00:00Z",
    "nvd_published_at": "2026-03-25T17:16:56Z",
    "severity": "MODERATE"
  },
  "details": "Mattermost versions 11.2.x \u003c= 11.2.2, 10.11.x \u003c= 10.11.10, 11.4.x \u003c= 11.4.0, 11.3.x \u003c= 11.3.1 fail to properly validate CSRF tokens in the /api/v4/access_control_policies/{policy_id}/activate endpoint, which allows an attacker to trick an admin into changing access control policy active status via a crafted request. Mattermost Advisory ID: MMSA-2026-00578",
  "id": "GHSA-rmhw-c3xr-m3xx",
  "modified": "2026-03-31T23:00:00Z",
  "published": "2026-03-25T18:31:53Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27659"
    },
    {
      "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:R/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Mattermost doesn\u0027t properly validate CSRF tokens"
}

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.

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.

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.

Action not permitted

CVE-2026-27659 (GCVE-0-2026-27659)

CERTFR-2026-AVI-0201

Solutions

FKIE_CVE-2026-27659

GHSA-RMHW-C3XR-M3XX

Tags

Sightings

Nomenclature

Related by attack behaviour