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High, CVSS 7.5amended

matrix-js-sdk subject to impersonated messages due to permissive key forwarding

CVE-2022-39249GHSA-6263-x97c-c4gg

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (matrix-js-sdk 19.7.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS
  • CVE-2022-39249: 1.28% estimated exploitation activity in the next 30 days; percentile 69.97 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Impact 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 forwarding strategy on the receiving end. Key forwarding is a mechanism allowing clients to recover from “unable to decrypt” messages when they missed the initial key distribution, at the time the message was originally sent. Examples include accessing message history before they joined the room but also when some network/federation errors have occurred. Patches The default policy for accepting key forwards has been made more strict in the matrix-js-sdk. matrix-js-sdk will now only accept forwarded keys in response to previously issued requests and only from own, verified devices. A unique exception to this rule is with the experimental MSC3061, that is forwarding room keys for…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-6263-x97c-c4gg

  2. Revision 1 · created ·

    Published from osv record GHSA-6263-x97c-c4gg

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2022-39249

Advisory: matrix-js-sdk subject to impersonated messages due to permissive key forwarding
IDs: CVE-2022-39249, GHSA-6263-x97c-c4gg
Record: https://patchnext.com/advisories/cve-2022-39249 (revision 2, source checked 26 Oct 2026, 12:17 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: matrix-js-sdk 19.7.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm matrix-js-sdk: affected < 19.7.0; fixed in 19.7.0

## Suggested inspection (read-only)
- `npm ls matrix-js-sdk --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on matrix-js-sdk.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-6263-x97c-c4gg (OSV record GHSA-6263-x97c-c4gg lists affected ranges: npm matrix-js-sdk >=0 <19.7.0 (fixed))
- Verified: https://github.com/advisories/GHSA-6263-x97c-c4gg (GitHub-reviewed advisory GHSA-6263-x97c-c4gg lists affected ranges: npm matrix-js-sdk >=0 <19.7.0)

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