Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to filter nil elements from outgoing webhook attachment payloads bef…

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

1. May 25, 2026 · NIST NVD

   Detected

   Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to filter nil elements from outgoing webhook attachment payloads before processing, which allows an authenticated user to cause a denial of service (server process termination) via a crafted webhook callback response containing a null attachment entry.. Mattermost Advisory ID: MMSA-2026-00641

2. Jul 23, 2026 · NIST NVD

   Updated

   Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to filter nil elements from outgoing webhook attachment payloads before processing, which allows an authenticated user to cause a denial of service (server process termination) via a crafted webhook callback response containing a null attachment entry.. Mattermost Advisory ID: MMSA-2026-00641

Affected

• cpe mattermost/mattermost serverversion unspecified

Sources

• CVE.orgVulnerability recordCVE-2026-4915

  Official CVE identifier

  cve.org
• NIST NVDVulnerability recordCVE-2026-4915

  Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to filter nil elements from outgoing webhook attachment payloads before processing, which allows an authenticated user to cause a denial of service (server process termination) via

  nvd.nist.gov

References

• Vendor Advisory · mattermost.com