matrix-android-sdk2 vulnerable to Olm/Megolm protocol confusion

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.6 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N

EPSS

• CVE-2022-39248: 1.00% estimated exploitation activity in the next 30 days; percentile 62.73 (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 that legitimately appear to have come from another person, without any indication such as a grey shield. Additionally, a sophisticated attacker cooperating with a malicious homeserver could employ this vulnerability to perform a targeted attack in order to send fake to-device messages appearing to originate from another user. This can allow, for example, to inject the key backup secret during a self-verification, to make a targeted device start using a malicious key backup spoofed by the homeserver. matrix-android-sdk2 would then additionally sign such a key backup with its device key, spilling trust over to other devices trusting the matrix-android-sdk2 device. These attacks are possible due to a protocol confusion vulnerability that accepts to-device messages encrypted with Megolm instead of Olm. Patches matrix-android-sdk2 has been modified to only accept Olm-encrypted to-device messages and to stop…

Published by the source

30 Sep 2022, 04:37 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-fpgf-pjjv-2qgm

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# Patch Next advisory brief: CVE-2022-39248

Advisory: matrix-android-sdk2 vulnerable to Olm/Megolm protocol confusion
IDs: CVE-2022-39248, GHSA-fpgf-pjjv-2qgm
Record: https://patchnext.com/advisories/cve-2022-39248 (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 8.6)
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-fpgf-pjjv-2qgm (GitHub-reviewed advisory GHSA-fpgf-pjjv-2qgm lists affected ranges: Maven org.matrix.android:matrix-android-sdk2 >=0 <=1.4.36)

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