CVE-2018-12291
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.79%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.0
- 7.5 HIGHCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- EPSS
- 1.79% probability · 78th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Affected
- matrix/synapse
- Source
- cve@mitre.org
EPSS 1.8% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://github.com/matrix-org/synapse/pull/3371Patch, Third Party Advisory
- https://github.com/matrix-org/synapse/releases/tag/v0.31.1Third Party Advisory
- https://github.com/matrix-org/synapse/pull/3371Patch, Third Party Advisory
- https://github.com/matrix-org/synapse/releases/tag/v0.31.1Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.