Matrix Synapse Authorization Error

HIGH 7.5CVE-2018-12423 · GHSA-ch5v-fhg8-7gv9 · PYSEC-2026-844 · Published 14/06/2018 · updated 17/06/2026

In short

CVE-2018-12423 is a HIGH (CVSS 7.5) vulnerability affecting matrix-synapse, synapse (matrix).
Chance of exploitation in the next 30 days (EPSS): 1.8%, higher than 78.6% of all vulnerabilities.
Fix: update to 0.31.2 or later.

Package	Affected versions	Patched versions
matrix-synapse PyPI	`< 0.31.2`	`0.31.2`
synapse matrix	`< 0.31.2`	`0.31.2`

In Synapse before 0.31.2, unauthorised users can hijack rooms when there is no m.room.power_levels event in force.

NVD description

In Synapse before 0.31.2, unauthorised users can hijack rooms when there is no m.room.power_levels event in force.

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Package

Affected versions

Patched versions

PyPI

< 0.31.2

0.31.2

< 0.31.2

0.31.2

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