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MEDIUM severity

CVE-2025-12689 — mattermost-plugin-calls

MEDIUMFix: mattermost/mattermost-plugin-calls@f68b419

CVE-2025-12689 is a medium-severity (CVSS 6.5) CWE-1287 vulnerability in github.com/mattermost/mattermost-plugin-calls. A fix is available for github.com/mattermost/mattermost-plugin-calls — see the affected versions and patch details below.

DoS in Calls plugin via malformed UTF-8 in WebSocket request

Also known asGHSA-j5vq-62gr-8v3rGO-2025-4255
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2025-12689.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs21th percentile — riskier than 21% of all scored CVEsHighest risk
0.00%0.26%0.53%0.79%0.1%0.3%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐹github.com/mattermost/mattermost-plugin-calls

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 11.0.x <= 11.0.4, 10.12.x <= 10.12.2, 10.11.x <= 10.11.6 fail to check WebSocket request field for proper UTF-8 format, which allows attacker to crash Calls plug-in via sending malformed request.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/mattermost/mattermost-plugin-callsall versions1.11.0go get github.com/mattermost/mattermost-plugin-calls@v1.11.0

Affected Products

1 product · 3 configurations
Application
mattermost servermattermost
≥ 11.0.0 && < 11.0.5
range

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-plugin-calls, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update github.com/mattermost/mattermost-plugin-calls to 1.11.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-12689 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.

Frequently Asked Questions

Mattermost versions 11.0.x <= 11.0.4, 10.12.x <= 10.12.2, 10.11.x <= 10.11.6 fail to check WebSocket request field for proper UTF-8 format, which allows attacker to crash Calls plug-in via sending malformed request.
O3 Security · Impact-Aware SCA

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CVE-2025-12689: mattermost-plugin-calls — Fixed in 1.11.0