Prototype pollution in matrix-js-sdk (part 2) (CVE-2023-28427)

Prototype pollution in matrix-js-sdk (part 2) (CVE-2023-28427) | HOL Guard CVE

Why this deserves its current priority

CVSS is 8.2. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps matrix-js-sdk (npm). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
matrix-js-sdknpm	>=0 <24.0.0	24.0.0

Recommended response

Check inventory. Check lockfiles and deployed manifests for matrix-js-sdk.
Review the reported fix. Update matrix-js-sdk to 24.0.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Mar 30, 2023
Evidence: source:osv:source_dates:source-dates:record
Source modified
Sep 10, 2026
Evidence: source:osv:source_dates:source-dates:record
First seen by HOL
Sep 10, 2026

Sources and claim methodology

Upstream source description

### Impact In certain configurations, data sent by remote servers containing special strings in key locations could cause modifications of the `Object.prototype`, disrupting matrix-js-sdk functionality, causing denial of service and potentially affecting program logic. (This is part 2, where [CVE-2022-36059](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-36059) / [GHSA-rfv9-x7hh-xc32](https://github.com/matrix-org/matrix-js-sdk/security/advisories/GHSA-rfv9-x7hh-xc32) is part 1. Part 2 covers remaining vectors not covered by part 1, found in a codebase audit scheduled after part 1.) ### Patches The issue has been patched in matrix-js-sdk 24.0.0. ### Workarounds None. ### References - [Release blog post](https://matrix.org/blog/2023/03/28/security-releases-matrix-js-sdk-24-0-0-and-matrix-react-sdk-3-69-0) - The advisory [GHSA-rfv9-x7hh-xc32](https://github.com/matrix-org/matrix-js-sdk/security/advisories/GHSA-rfv9-x7hh-xc32) ([CVE-2022-36059](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-36059)) refers to an initial set of vulnerable locations discovered and patched in matrix-js-sdk 19.4.0. We opted not to disclose that advisory while we performed an audit of the codebase and are now disclosing it jointly with this one. ### For more information If you have any questions or comments about this advisory please email us at [security at matrix.org](mailto:[email protected]).

Quoted source text, attributed separately from HOL analysis.