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CVE-2026-5308

MEDIUM

Missing request body size limits on Zoom plugin HTTP endpoints

Also known asGHSA-jmvr-r5hm-fxfrGO-2026-5836
Published
May 22, 2026
Updated
Jul 8, 2026
Affected
5 pkgs
Patched
5 / 5
Exploits
None indexed

Blast Radius

5 pkgs affected
🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost-plugin-github

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

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 enforce request body size limits on plugin HTTP endpoints which allows an attacker to cause a denial of service via crafted oversized HTTP requests.. Mattermost Advisory ID: MMSA-2026-00646

Affected Packages

5 total 5 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/mattermost/mattermost-server11.6.0&&< 11.6.111.6.1
🐹Gogithub.com/mattermost/mattermost-server11.5.0&&< 11.5.411.5.4
🐹Gogithub.com/mattermost/mattermost-server11.4.0&&< 11.4.511.4.5
🐹Gogithub.com/mattermost/mattermost-server10.11.0&&< 10.11.1510.11.15
🐹Gogithub.com/mattermost/mattermost-plugin-githuball versions1.0.1-0.20260410143745-9b41b1fd43c4

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/mattermost/mattermost-server. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update github.com/mattermost/mattermost-server to 11.6.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-5308 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether CVE-2026-5308 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2026-5308. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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 enforce request body size limits on plugin HTTP endpoints which allows an attacker to cause a denial of service via crafted oversized HTTP requests.. Mattermost Advisory ID: MMSA-2026-00646
O3 Security · Impact-Aware SCA

Is CVE-2026-5308 in your dependencies?

O3 detects CVE-2026-5308 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.