GHSA-f3r3-h2mq-hx2h — matrix-synapse
GHSA-f3r3-h2mq-hx2h is a Improper Input Validation vulnerability in matrix-synapse. A fix is available for matrix-synapse — see the affected versions and patch details below.
Synapse allows a a malformed invite to break the invitee's `/sync`
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- 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-f3r3-h2mq-hx2h.
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.
Real-World Exposure
matrix-synapseReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Impact
Synapse versions before 1.120.1 fail to properly validate invites received over federation. This vulnerability allows a malicious server to send a specially crafted invite that disrupts the invited user's /sync functionality.
Patches
Synapse 1.120.1 rejects such invalid invites received over federation and restores the ability to sync for affected users.
Workarounds
Server administrators can disable federation from untrusted servers.
For more information
If you have any questions or comments about this advisory, please email us at security at element.io.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | matrix-synapse | all versions | 1.120.1pip install --upgrade 'matrix-synapse==1.120.1' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for matrix-synapse, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update matrix-synapse to 1.120.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-f3r3-h2mq-hx2h 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-f3r3-h2mq-hx2h can be triaged on real exposure rather than presence alone.
Tailored to GHSA-f3r3-h2mq-hx2h. 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-f3r3-h2mq-hx2h in your dependencies?
O3 Security finds GHSA-f3r3-h2mq-hx2h across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.