matrix-android-sdk2 vulnerable to impersonation via forwarded Megolm sessions

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-2022-39246: 0.87% estimated exploitation activity in the next 30 days; percentile 58.76 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

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-android-sdk2 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-android-sdk2. The matrix-android-sdk2 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…

Published by the source

30 Sep 2022, 04:33 UTC

Last modified by the source

29 Jan 2023, 05:05 UTC

Source last checked

26 Oct 2026, 16:02 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-2pvj-p485-cp3m

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# Patch Next advisory brief: CVE-2022-39246

Advisory: matrix-android-sdk2 vulnerable to impersonation via forwarded Megolm sessions
IDs: CVE-2022-39246, GHSA-2pvj-p485-cp3m
Record: https://patchnext.com/advisories/cve-2022-39246 (revision 1, source checked 26 Oct 2026, 16:02 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: org.matrix.android:matrix-android-sdk2 1.5.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.matrix.android:matrix-android-sdk2: affected <= 1.4.36; fixed in 1.5.1

## Suggested inspection (read-only)
- Maven org.matrix.android:matrix-android-sdk2: check the installed version with your package manager.

## 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 org.matrix.android:matrix-android-sdk2.
- 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://github.com/advisories/GHSA-2pvj-p485-cp3m (GitHub-reviewed advisory GHSA-2pvj-p485-cp3m lists affected ranges: Maven org.matrix.android:matrix-android-sdk2 >=0 <=1.4.36)

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