CVE-2025-24024: Mjolnir v1.9.0 accepts commands from any room

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-01-21 · updated 2026-06-17
Weakness: CWE-671

Description

Mjolnir is a moderation tool for Matrix. Mjolnir v1.9.0 responds to management commands from any room the bot is member of. This can allow users who aren't operators of the bot to use the bot's functions, including server administration components if enabled. Version 1.9.1 reverts the feature that introduced the bug, and version 1.9.2 reintroduces the feature safely. Downgrading to version 1.8.3 is recommended if upgrading to 1.9.1 or higher isn't possible.

Affected products

matrix-org mjolnir: = 1.9.0

References

https://github.com/matrix-org/mjolnir/commit/b437fa16b5425985715df861987c836affd51eea
https://github.com/matrix-org/mjolnir/commit/d0ef527a9e3eb45e17143d5295a64b775ccaa23d
https://github.com/matrix-org/mjolnir/security/advisories/GHSA-3jq6-xc85-m394

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