CVE-2022-39249 — Matrix Javascript SDK is the Matrix Client-Server SDK for JavaScript

Matrix Javascript SDK is the Matrix Client-Server SDK for JavaScript. Prior to version 19.7.0, an attacker cooperating with a malicious homeserver can construct messages appearing to have come from another person. Such messages will be marked with a grey shield on some platforms,

01What is this vulnerability?

Matrix Javascript SDK is the Matrix Client-Server SDK for JavaScript. Prior to version 19.7.0, an attacker cooperating with a malicious homeserver can construct messages appearing to have come from another person. Such messages will be marked with a grey shield on some platforms, but this may be missing in others. This attack is possible due to the matrix-js-sdk implementing a too permissive key…

02Affected products

Vendor	Product	Versions
matrix-org	matrix	js-sdk — < 19.7.0

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2022-09-28T00:00:00.000Z
• Last modified: 2025-04-23T16:55:11.362Z

09References

• github.com — https://github.com/matrix-org/matrix-js-sdk/commit/a587d7c36026fe1fcf93dfff63588…
• github.com — https://github.com/matrix-org/matrix-js-sdk/releases/tag/v19.7.0
• github.com — https://github.com/matrix-org/matrix-js-sdk/security/advisories/GHSA-6263-x97c-c…
• github.com — https://github.com/matrix-org/matrix-spec-proposals/pull/3061
• matrix.org — https://matrix.org/blog/2022/09/28/upgrade-now-to-address-encryption-vulns-in-ma…
• security.gentoo.org — https://security.gentoo.org/glsa/202210-35