Vulnerability-Lookup

CERTFR-2026-AVI-1098

Vulnerability from certfr_avis - Published: 2026-09-01 - Updated: 2026-09-15

De multiples vulnérabilités ont été découvertes dans Mattermost Server. Elles permettent à un attaquant de provoquer 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 11.8.x antérieures à 11.8.5
Mattermost	Mattermost Server	Mattermost Server versions 11.7.x antérieures à 11.7.8
Mattermost	Mattermost Server	Mattermost Server versions 11.9.x antérieures à 11.9.1

References

Title

Publication Time

CVE-2026-12985 (GCVE-0-2026-12985)

Vulnerability from cvelistv5 – Published: 2026-09-14 14:09 – Updated: 2026-09-15 03:56

Title

Mattermost DCR redirect URI allowlist bypass via improper URL component validation

Summary

Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7 Mattermost failed to validate Dynamic Client Registration redirect URIs by URL component (matching glob patterns against the raw URI string instead) which allows a remote unauthenticated attacker to register an OAuth client with an attacker-controlled callback host that bypasses the configured redirect URI allowlist via a crafted redirect URI that places an allowlisted host/path suffix inside the query string.. Mattermost Advisory ID: MMSA-2026-00700

Severity

6.8 (Medium)


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

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-14 00:00 UTC

CWE

CWE-601 - URL Redirection to Untrusted Site (“Open Redirect”)

Assigner

Mattermost CNA under the mitre root

CNA scorecard B 80/100 over 122 records in the last 180 days details

References

1 reference

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

Impacted products

1 product

Vendor	Product	Version
Mattermost	Mattermost	Affected: 11.9.0 , ≤ 11.9.0 (semver) Affected: 11.8.0 , ≤ 11.8.4 (semver) Affected: 11.7.0 , ≤ 11.7.7 (semver) Unaffected: 11.10.0 Unaffected: 11.9.1 Unaffected: 11.8.5 Unaffected: 11.7.8

Credits

aryangurjarf401a3

Show details on NVD website

JSON

To clipboard

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                "id": "CVE-2026-12985",
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            "confidentialityImpact": "HIGH",
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            }
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        "advisory": "MMSA-2026-00700",
        "defect": [
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        "discovery": "EXTERNAL"
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      "title": "Mattermost DCR redirect URI allowlist bypass via improper URL component validation",
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    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

CVE-2026-82920 (GCVE-0-2026-82920)

Vulnerability from cvelistv5 – Published: 2026-09-14 13:59 – Updated: 2026-09-14 19:23

Title

Mattermost ABAC parent policy bypass via policy update endpoint

Summary

Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7 fail to enforce authorization boundaries on the access control policy update endpoint which allows a channel or team administrator to detach a system-assigned ABAC parent policy via a crafted PUT /api/v4/access_control_policies request with an empty imports list.. Mattermost Advisory ID: MMSA-2026-00724

Severity

5.5 (Medium)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-14 19:13 UTC

CWE

CWE-863 - Incorrect Authorization

Assigner

Mattermost CNA under the mitre root

CNA scorecard B 80/100 over 122 records in the last 180 days details

References

1 reference

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

Impacted products

1 product

Vendor	Product	Version
Mattermost	Mattermost	Affected: 11.9.0 , ≤ 11.9.0 (semver) Affected: 11.8.0 , ≤ 11.8.4 (semver) Affected: 11.7.0 , ≤ 11.7.7 (semver) Unaffected: 11.10.0 Unaffected: 11.9.1 Unaffected: 11.8.5 Unaffected: 11.7.8

Credits

kiwi_71

Show details on NVD website

JSON

To clipboard

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        "metrics": [
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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.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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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

CERTFR-2026-AVI-1098

Solutions

CVE-2026-12985 (GCVE-0-2026-12985)

CVE-2026-82920 (GCVE-0-2026-82920)

Tags

Sightings

Nomenclature

Vulnerability timeline

Related by attack behaviour