matrix-js-sdk can be tricked into disclosing E2EE room keys to a participating homeserver
Impact
A logic error in the room key sharing functionality of matrix-js-sdk before 12.4.1 allows a malicious Matrix homeserver† participating in an encrypted room to steal room encryption keys from affected Matrix clients participating in that room. This allows the homeserver to decrypt end-to-end encrypted messages sent by affected clients.
† Or anyone with access to the account of the original recipient of an encrypted message.
Known clients affected (via their use of vulnerable versions of matrix-js-sdk):
- Element Web (1.8.2 and earlier)
- Element Desktop (1.8.2 and earlier)
- SchildiChat Web (1.7.32-sc1 and earlier)
- SchildiChat Desktop (1.7.32-sc1 and earlier)
- Cinny (1.2.0 and earlier)
Patch
This was fixed in https://github.com/matrix-org/matrix-js-sdk/commit/894c24880da0e1cc81818f51c0db80e3c9fb2be9.
Workarounds
To prevent a homeserver from being able to steal the room keys, vulnerable clients can be taken offline or signed out. If signing out, care should be taken to either set up Secure Backup or export E2E room keys in order to preserve access to past messages.
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| Paquete de npm | matrix-js-sdk | < 12.4.1 | 12.4.1 |
Referencias
- https://github.com/matrix-org/matrix-js-sdk/security/advisories/GHSA-23cm-x6j7-6hq3
- https://nvd.nist.gov/vuln/detail/CVE-2021-40823
- https://github.com/matrix-org/matrix-js-sdk/commit/894c24880da0e1cc81818f51c0db80e3c9fb2be9
- https://github.com/matrix-org/matrix-js-sdk
- https://github.com/matrix-org/matrix-js-sdk/releases/tag/v12.4.1
- https://matrix.org/blog/2021/09/13/vulnerability-disclosure-key-sharing
- Vector CVSS
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N- Debilidad (CWE)
CWE-200, CWE-327- Plataforma
- npm
- Paquete
matrix-js-sdk- Publicada
- 14.09.2021
- Actualizado
- 11.10.2026 10:22
Fuentes y licencias
OSV / GitHub Advisory Database - GHSA-23cm-x6j7-6hq3 - CC BY 4.0
Historial de vulnerabilidades: matrix-js-sdk
Todas las vulnerabilidades publicadas de este paquete (Paquete de npm), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.
- Entradas en total
- 12
- Primera → última
- 09.2021 09.2025
- Sin corrección
- 0
- Explotada en ataques
- 0
Distribución por gravedad
- Alta 6
- Media 6
Divulgaciones por año
- 2021: 1
- 2022: 4
- 2023: 3
- 2024: 3
- 2025: 1
- 2026: 0
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matrix-js-sdk can be tricked into disclosing E2EE room keys to a participating homeserver esta entrada
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