How severe is CVE-2023-38700?

CVE-2023-38700 has a CVSS score of 3.5/10, rated LOW. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2023-38700?

CVE-2023-38700 affects the following packages: matrix-appservice-irc (npm). Ecosystems affected: npm.

How do I fix CVE-2023-38700?

Update matrix-appservice-irc to 1.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-38700 is resolved across your whole dependency graph.

How do I detect CVE-2023-38700 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 CVE-2023-38700 if there is no patch (or I can't update yet)?

Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.

Is CVE-2023-38700 actively exploited in the wild?

No public exploit code has been indexed for CVE-2023-38700 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 CVE-2023-38700?

CVE-2023-38700 has an EPSS (Exploit Prediction Scoring System) score of 0.6%, placing it in the 49th 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 CVE-2023-38700?

CVE-2023-38700 is classified as Information Exposure (CWE-200). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2023-38700 published, and has it been updated?

CVE-2023-38700 was published on August 4, 2023 and was last updated on October 28, 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

LOW severity

CVE-2023-38700 — matrix-appservice-irc

LOWFix: matrix-org/matrix-appservice-irc@8bbd2b6

CVE-2023-38700 is a low-severity (CVSS 3.5) Information Exposure vulnerability in matrix-appservice-irc. A fix is available for matrix-appservice-irc — see the affected versions and patch details below.

matrix-appservice-irc events can be crafted to leak parts of targeted messages from other bridged rooms

Also known asGHSA-c7hh-3v6c-fj4q

Published

Aug 4, 2023

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 8, 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 CVE-2023-38700.

EPSS Exploitation Probability

via FIRST.org ↗

0.6%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs49th percentile — riskier than 49% 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

519downloads / week

Description

Impact

It was possible to craft an event such that it would leak part of a targeted message event from another bridged room. This required knowing an event ID to target.

Patches

Please upgrade to 1.0.1.

Workarounds

You can set the matrixHandler.eventCacheSize config value to 0 to workaround this bug. However, this may impact performance.

Credits

Discovered and reported by Val Lorentz.

For more information

If you have any questions or comments about this advisory email us at [email protected].

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`matrix-appservice-irc`	all versions	1.0.1`npm install matrix-appservice-irc@1.0.1`

Affected Products

1 product · 1 configurations

Application

matrix irc bridgematrix

< 1.0.1

range

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 1.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-38700 is resolved across your whole dependency graph.
Workarounds
Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.

Frequently Asked Questions

### Impact It was possible to craft an event such that it would leak part of a targeted message event from another bridged room. This required knowing an event ID to target. ### Patches Please upgrade to 1.0.1. ### Workarounds You can set the `matrixHandler.eventCacheSize` config value to `0` to workaround this bug. However, this may impact performance. ### Credits Discovered and reported by [Val Lorentz](https://valentin-lorentz.fr/). ### For more information If you have any questions or comments about this advisory email us at [[email protected]](mailto:[email protected]).