# CVE-2026-116516: Mattermost Agents plugin denial of service via Zoom chat summarization

Source: https://junglewise.ai/threats/cve-2026-116516-mattermost-versions-11-9-11-1-9-11-5-8-11-10-7-0-fail-to  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-26. Updated: 2026-10-26  
License: CC BY 4.0 with a link back

CVE-2026-116516 · Severity: medium · CVSS 6.5 · Published 2026-10-26

Mattermost's Agents plugin fails to properly validate the length of chat lines when processing Zoom transcriptions before attempting to parse them. An authenticated user can exploit this by summarizing a specially crafted Zoom chat transcription, causing the plugin to crash and become unavailable to other users.

Vendors: [Mattermost](https://junglewise.ai/threats/vendors/mattermost).

## Quick answers

**Is CVE-2026-116516 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-116516 being exploited in the wild.

**How severe is CVE-2026-116516?** Medium severity, with a CVSS score of 6.5, published 26 October 2026.

**Which products and versions are affected?** Mattermost Agents plugin versions 11.1.9, 11.5.8, 11.9, 11.10.7.0 and earlier.

**Is there a fix for CVE-2026-116516?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-116516 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-116516?** Check whether you run Mattermost Agents plugin at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability exists in the Zoom chat line processing logic of the Agents plugin, where insufficient validation of chat line length before string slicing operations allows an out-of-bounds or malformed data condition. An authenticated attacker can trigger a denial of service by initiating a summarization operation on a Zoom transcription containing specially crafted short continuation lines, causing the plugin process to crash.

## Affected products

- Mattermost Agents plugin versions 11.1.9, 11.5.8, 11.9, 11.10.7.0 and earlier

## Timeline

- 2026-10-26: disclosed

## References

- [https://mattermost.com/security-updates](https://mattermost.com/security-updates)