GHSA-59hf-mpf8-pqjh
MEDIUMMattermost fails to strip `embeds` from `metadata` when broadcasting `posted` events
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
github.com/mattermost/mattermost/server/v8Real-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 does not strip embeds from metadata when broadcasting posted events.
This allows users to include arbitrary embeds in posts, which are then broadcasted via websockets. This can be exploited in many ways, for example to create permalinks with fully customizable content or to trigger a client Side Denial of Service (DoS) by sending a permalink with a non-string message.
The advisory metadata references the appropriate go pseudo version available from pkg.go.dev
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/mattermost/mattermost/server/v8 | all versions | 8.0.0-20240806094731-69a8b3df0f9f |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/mattermost/mattermost/server/v8. 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.
Fix
Update github.com/mattermost/mattermost/server/v8 to 8.0.0-20240806094731-69a8b3df0f9f or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-59hf-mpf8-pqjh is resolved across your whole dependency graph.
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.
How O3 protects you
O3 pinpoints whether GHSA-59hf-mpf8-pqjh 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 GHSA-59hf-mpf8-pqjh. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-59hf-mpf8-pqjh in your dependencies?
O3 detects GHSA-59hf-mpf8-pqjh across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.