GHSA-vc2m-hw89-qjxf — matrix-media-repo
MEDIUMGHSA-vc2m-hw89-qjxf is a medium-severity (CVSS 5.3) CWE-770 vulnerability in github.com/t2bot/matrix-media-repo. A fix is available for github.com/t2bot/matrix-media-repo — see the affected versions and patch details below.
matrix-media-repo (MMR) allows denial of service/high operating costs through unauthenticated downloads
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-vc2m-hw89-qjxf.
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.
How urgent is this, really
GHSA-vc2m-hw89-qjxf plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/t2bot/matrix-media-repoReal-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
Impact
MMR before version 1.3.5 is vulnerable to unbounded disk consumption, where an unauthenticated adversary can induce it to download and cache large amounts of remote media files.
MMR's typical operating environment uses S3-like storage as a backend, with file-backed store as an alternative option. Instances using a file-backed store or those which self-host an S3 storage system are therefore vulnerable to a disk fill attack. Once the disk is full, authenticated users will be unable to upload new media, resulting in denial of service.
For instances configured to use a cloud-based S3 storage option, this could result in high service fees instead of a denial of service.
Patches
MMR 1.3.5 introduces a new default-on "leaky bucket" rate limit to reduce the amount of data a user can request at a time. This does not fully address the issue, but does limit an unauthenticated user's ability to request large amounts of data.
Operators should note that the leaky bucket implementation introduced in MMR 1.3.5 requires the IP address associated with the request to be forwarded, to avoid mistakenly applying the rate limit to the reverse proxy instead. To avoid this issue, the reverse proxy should populate the X-Forwarded-For header when sending the request to MMR.
Workarounds
Operators may wish to lower the maximum file size they allow and implement harsh rate limits, though this can still lead to a large amount of data to be downloaded.
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/t2bot/matrix-media-repo | all versions | 1.3.5go get github.com/t2bot/matrix-media-repo@v1.3.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/t2bot/matrix-media-repo, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/t2bot/matrix-media-repo to 1.3.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-vc2m-hw89-qjxf 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-vc2m-hw89-qjxf can be triaged on real exposure rather than presence alone.
Tailored to GHSA-vc2m-hw89-qjxf. 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-vc2m-hw89-qjxf in your dependencies?
O3 Security finds GHSA-vc2m-hw89-qjxf across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.