How severe is GHSA-w9mh-5x8j-9754?

GHSA-w9mh-5x8j-9754 has a CVSS score of 4.3/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by GHSA-w9mh-5x8j-9754?

GHSA-w9mh-5x8j-9754 affects the following packages: matrix-appservice-irc (npm). Ecosystems affected: npm.

How do I fix GHSA-w9mh-5x8j-9754?

Update matrix-appservice-irc to 2.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-w9mh-5x8j-9754 is resolved across your whole dependency graph.

How do I detect GHSA-w9mh-5x8j-9754 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for matrix-appservice-irc, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-w9mh-5x8j-9754 if there is no patch (or I can't update yet)?

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.

Is GHSA-w9mh-5x8j-9754 actively exploited in the wild?

No public exploit code has been indexed for GHSA-w9mh-5x8j-9754 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-w9mh-5x8j-9754?

GHSA-w9mh-5x8j-9754 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 43th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-w9mh-5x8j-9754?

GHSA-w9mh-5x8j-9754 is classified as CWE-280 (CWE-280), CWE-755 (CWE-755). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-w9mh-5x8j-9754 published, and has it been updated?

GHSA-w9mh-5x8j-9754 was published on July 5, 2024 and was last updated on September 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

MEDIUM severity

Malicious Matrix homeserver can leak truncated message content of messages it shouldn't have access toGHSA-w9mh-5x8j-9754

MEDIUMFix: matrix-org/matrix-appservice-irc#1804

GHSA-w9mh-5x8j-9754 is a medium-severity (CVSS 4.3) CWE-280 vulnerability in matrix-appservice-irc. A fix is available for matrix-appservice-irc — see the affected versions and patch details below.

Also known asCVE-2024-39691

Published

Jul 5, 2024

Updated

Sep 10, 2026

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 GHSA-w9mh-5x8j-9754.

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs43th percentile — riskier than 43% of all scored CVEsHighest risk

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

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

0other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

matrix-appservice-ircnpm

474downloads / week

Description

Impact

The fix for GHSA-wm4w-7h2q-3pf7 / CVE-2024-32000 included in matrix-appservice-irc 2.0.0 relied on the Matrix homeserver-provided timestamp to determine whether a user has access to the event they're replying to when determining whether or not to include a truncated version of the original event in the IRC message. Since this value is controlled by external entities, a malicious Matrix homeserver joined to a room in which a matrix-appservice-irc bridge instance (before version 2.0.1) is present can fabricate the timestamp with the intent of tricking the bridge into leaking room messages the homeserver should not have access to.

Patches

matrix-appservice-irc 2.0.1 drops the reliance on origin_server_ts when determining whether or not an event should be visible to a user, instead tracking the event timestamps internally.

Workarounds

It's possible to limit the amount of information leaked by setting a reply template that doesn't contain the original message. See these lines in the configuration file.

References

Patch: https://github.com/matrix-org/matrix-appservice-irc/pull/1804

For more information

If you have any questions or comments about this advisory, please email us at security at matrix.org.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`matrix-appservice-irc`	all versions	2.0.1`npm install matrix-appservice-irc@2.0.1`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for matrix-appservice-irc, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update matrix-appservice-irc to 2.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-w9mh-5x8j-9754 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.

Frequently Asked Questions

### Impact The fix for GHSA-wm4w-7h2q-3pf7 / [CVE-2024-32000](https://www.cve.org/CVERecord?id=CVE-2024-32000) included in matrix-appservice-irc 2.0.0 relied on the Matrix homeserver-provided timestamp to determine whether a user has access to the event they're replying to when determining whether or not to include a truncated version of the original event in the IRC message. Since this value is controlled by external entities, a malicious Matrix homeserver joined to a room in which a matrix-appservice-irc bridge instance (before version 2.0.1) is present can fabricate the timestamp with the