Vulnerability-Lookup

CVE-2026-6673 (GCVE-0-2026-6673)

Vulnerability from cvelistv5 – Published: 2026-06-22 13:38 – Updated: 2026-06-22 15:41

Title

Mattermost Jira plugin had unauthenticated {{/ac/installed}} lifecycle callback during pending Jira Cloud install

Summary

Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret and disrupt the Jira integration via POST to /ac/installed during the pending-install window.. Mattermost Advisory ID: MMSA-2026-00654

Severity

6.4 (Medium)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-06-22 15:40 UTC

CWE

CWE-306 - Missing Authentication for Critical Function

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: 11.7.0 , ≤ 11.7.0 (semver) Affected: 11.6.0 , ≤ 11.6.2 (semver) Affected: 11.5.0 , ≤ 11.5.5 (semver) Affected: 10.11.0 , ≤ 10.11.17 (semver) Unaffected: 11.8.0 Unaffected: 11.7.1 Unaffected: 11.6.3 Unaffected: 11.5.6 Unaffected: 10.11.18	guessed

Credits

insomnia1102

Show details on NVD website

JSON

To clipboard

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}

CERTFR-2026-AVI-0632

Vulnerability from certfr_avis - Published: 2026-05-22 - Updated: 2026-08-14

De multiples vulnérabilités ont été découvertes dans les produits Mattermost. Elles permettent à un attaquant de provoquer un contournement de la politique de sécurité et un problème de sécurité non spécifié par l'éditeur.

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 Desktop App	Mattermost Desktop App versions 6.x antérieures à 6.2
Mattermost	Mattermost Server	Mattermost Server versions 11.5.x antérieures à 11.5.6
Mattermost	Mattermost Server	Mattermost Server versions 11.6.x antérieures à 11.6.3
Mattermost	Mattermost Desktop App	Mattermost Desktop App versions antérieures à 5.13.6
Mattermost	Mattermost Server	Mattermost Server versions 11.7.x antérieures à 11.7.1
Mattermost	Mattermost Server	Mattermost Server versions 10.11.x antérieures à 10.11.18

References

Title

Publication Time

FKIE_CVE-2026-6673

Vulnerability from fkie_nvd - Published: 2026-06-22 14:17 - Updated: 2026-06-23 20:49

Severity

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

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

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Mattermost",
          "vendor": "Mattermost",
          "versions": [
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            },
            {
              "status": "unaffected",
              "version": "11.6.3"
            },
            {
              "status": "unaffected",
              "version": "11.5.6"
            },
            {
              "status": "unaffected",
              "version": "10.11.18"
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              "versionStartIncluding": "10.11.0",
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    }
  ],
  "id": "CVE-2026-6673",
  "lastModified": "2026-06-23T20:49:21.050",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 6.4,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.2,
        "impactScore": 5.2,
        "source": "responsibledisclosure@mattermost.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-6673",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-06-22T15:40:53.578692Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-06-22T14:17:51.260",
  "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-306"
        }
      ],
      "source": "responsibledisclosure@mattermost.com",
      "type": "Secondary"
    }
  ]
}

GHSA-JQGV-39MG-7C2R

Vulnerability from github – Published: 2026-06-22 15:30 – Updated: 2026-09-15 19:50

Summary

Mattermost doesn't authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret

Details

Severity

6.4 (Medium)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/mattermost/mattermost-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "11.7.0"
            },
            {
              "fixed": "11.7.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/mattermost/mattermost-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "11.6.0"
            },
            {
              "fixed": "11.6.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/mattermost/mattermost-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "11.5.0"
            },
            {
              "fixed": "11.5.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/mattermost/mattermost-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "10.11.0"
            },
            {
              "fixed": "10.11.18"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-6673"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-306"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-15T19:50:55Z",
    "nvd_published_at": "2026-06-22T14:17:51Z",
    "severity": "MODERATE"
  },
  "details": "Mattermost versions 11.7.x \u003c= 11.7.0, 11.6.x \u003c= 11.6.2, 11.5.x \u003c= 11.5.5, 10.11.x \u003c= 10.11.17 fail to authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret and disrupt the Jira integration via POST to /ac/installed during the pending-install window.. Mattermost Advisory ID: MMSA-2026-00654",
  "id": "GHSA-jqgv-39mg-7c2r",
  "modified": "2026-09-15T19:50:55Z",
  "published": "2026-06-22T15:30:45Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-6673"
    },
    {
      "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:H/PR:L/UI:R/S:U/C:N/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Mattermost doesn\u0027t authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret"
}

WID-SEC-W-2026-1650

Vulnerability from csaf_certbund - Published: 2026-05-21 22:00 - Updated: 2026-06-22 22:00

Summary

Mattermost (Desktop, Server und Mobile): Mehrere Schwachstellen

Severity

Mittel

Scope

6 vulnerabilities in this advisory, including CVE-2026-6673.

CVE-2026-6673

Known affected: 7 products

Open the full advisory

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.

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-2026-6673 (GCVE-0-2026-6673)

CERTFR-2026-AVI-0632

Solutions

FKIE_CVE-2026-6673

GHSA-JQGV-39MG-7C2R

WID-SEC-W-2026-1650

Tags

Sightings

Nomenclature

Related by attack behaviour