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Not in CISA KEV
LOW severity

Mattermost has an Observable Timing Discrepancy vulnerabilityGHSA-xr3w-rmvj-f6m7

LOWFix: mattermost/mattermost@38208b8

GHSA-xr3w-rmvj-f6m7 is a low-severity (CVSS 3.1) CWE-208 vulnerability in github.com/mattermost/mattermost/server/v8. A fix is available for github.com/mattermost/mattermost/server/v8 — see the affected versions and patch details below.

Also known asCVE-2025-54499GO-2025-4036
Published
Updated
Affected
3 pkgs
Patched
3 / 3
Exploits
None indexed
Exploitation data as of Nov 10, 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 GHSA-xr3w-rmvj-f6m7.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk+0.01%
Lower risk than most CVEs20th percentile — riskier than 20% of all scored CVEsHighest risk
0.00%0.26%0.52%0.78%0.0%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

3 pkgs affected
🐹github.com/mattermost/mattermost/server/v8🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost-server

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 10.5.x <= 10.5.10, 10.11.x <= 10.11.2 fail to use constant-time comparison for sensitive string comparisons which allows attackers to exploit timing oracles to perform byte-by-byte brute force attacks via response time analysis on Cloud API keys and OAuth client secrets.

Affected Packages

3 total 3 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/mattermost/mattermost/server/v8all versions8.0.0-20250728063359-38208b8f065fgo get github.com/mattermost/mattermost/server/v8@v8.0.0-20250728063359-38208b8f065f
🐹Gogithub.com/mattermost/mattermost-server≥ 10.5.0&&< 10.5.1110.5.11go get github.com/mattermost/mattermost-server@v10.5.11
🐹Gogithub.com/mattermost/mattermost-server≥ 10.11.0&&< 10.11.310.11.3go get github.com/mattermost/mattermost-server@v10.11.3

Affected Products

1 product · 2 configurations
Application
mattermost servermattermost
≥ 10.11.0 && < 10.11.3
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/server/v8, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update github.com/mattermost/mattermost/server/v8 to 8.0.0-20250728063359-38208b8f065f or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xr3w-rmvj-f6m7 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 10.5.x <= 10.5.10, 10.11.x <= 10.11.2 fail to use constant-time comparison for sensitive string comparisons which allows attackers to exploit timing oracles to perform byte-by-byte brute force attacks via response time analysis on Cloud API keys and OAuth client secrets.
O3 Security · Impact-Aware SCA

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Mattermost has an Observable Timing Discrepancy…