CVE-2025-48937: matrix-sdk-crypto vulnerable to sender of encrypted events being spoofed by homeserver administrator

Severity: medium (CVSS 4.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-06-10 · updated 2026-06-17
Weakness: CWE-290

Description

matrix-rust-sdk is an implementation of a Matrix client-server library in Rust. matrix-sdk-crypto since version 0.8.0 and 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. This vulnerability is fixed in 0.11.1 and 0.12.0.

Affected products

matrix-org matrix-rust-sdk: from 0.8.0, < 0.11.1

References

https://github.com/matrix-org/matrix-rust-sdk/commit/13c1d2048286bbabf5e7bc6b015aafee98f04d55
https://github.com/matrix-org/matrix-rust-sdk/commit/56980745b4f27f7dc72ac296e6aa003e5d92a75b
https://github.com/matrix-org/matrix-rust-sdk/security/advisories/GHSA-x958-rvg6-956w
https://spec.matrix.org/v1.14/client-server-api/#mmegolmv1aes-sha2

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