Description
The on_get_missing_events function in handlers/federation.py in Matrix Synapse before 0.31.1 has a security bug in the get_missing_events federation API where event visibility rules were not applied correctly.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 18.04 LTS | matrix-synapse | 0.24.0+dfsg-1ubuntu0.1~esm1 | USN-6076-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | matrix-synapse | 1.43.0-1.1 | openSUSE-SU-2024:11041-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | matrix-synapse | < 0.31.1 | 0.31.1 | GHSA-v8wm-g9f2-xjv4 |
Advisories 2
- USN-6076-1 matrix-synapse vulnerabilities Ubuntu Security Notices (USN) · Feb 10, 2026
- openSUSE-SU-2024:11041-1 matrix-synapse-1.43.0-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026