🛡️ CVE-2025-48937 — matrix-sdk-crypto

🟡 CVSS 4.9 — Medium ✅ No Known Exploit CWE-290 NVD
4.9
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

matrix-sdk-crypto vulnerable to sender of encrypted events being spoofed by homeserver administrator

Summary

matrix-sdk-crypto since version 0.8.0 up to 0.11.0 does not correctly validate the sender of an encrypted event. Accordingly, a malicious homeserver operator can modify events served to clients, making those events appear to the recipient as if they were sent by another user.

Although the CVSS score is 4.9 (AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N), we consider this a High Severity security issue.

Details

The Matrix specification [requires](https://spec.matrix.org/v1.14/client-server-api/#mmegolmv1aes-sha2) that clients ensure that "the event’s sender, room_id, and the recorded session_id match a trusted session". The vulnerable matrix-sdk-crypto versions check that the room_id matches that of the session denoted by session_id, but do not check the sender.

Patches

The issue is resolved by [13c1d20](https://github.com/matrix-org/matrix-rust-sdk/commit/13c1d2048286bbabf5e7bc6b015aafee98f04d55), included in versions 0.11.1 and 0.12.0 of matrix-sdk-crypto.

Workarounds

Since a successful attack requires administrator access to the homeserver, users who trust the administrators of their local homeserver are not affected.

References

  • https://spec.matrix.org/v1.14/client-server-api/#mmegolmv1aes-sha2

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs administrative privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity high, availability none.

Weakness class

CVE-2025-48937 is classified as CWE-290: Authentication Bypass by Spoofing. Identity is inferred from something an attacker can forge, such as a header or address.

Affected software

CVE-2025-48937 is recorded against 2 packages.

  • matrix-sdk-crypto
  • unknown

Timeline and source

Published on 10 June 2025 and last revised on 12 June 2025. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Web)
github.com (Web)
github.com (Package)
rustsec.org (Web)
spec.matrix.org (Web)

Details

Severity Medium
CVSS Score 4.9
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N
CWE CWE-290
Public Exploit ✅ No
Source NVD
Published 2025-06-10
Updated 2026-08-12
Modified 2025-06-12
Fix URL N/A

Affected Packages

Software From version Fixed in
matrix-sdk-crypto — —
unknown — —

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