SB2026042391 - Improper Validation of Specified Type of Input in Synapse
Published: April 23, 2026
Security Bulletin ID
SB2026042391
CSH Severity
Low
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Data manipulation
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Improper Validation of Specified Type of Input (CVE-ID: CVE-2025-61672)
CWE-ID: CWE-1287 - Improper Validation of Specified Type of Input
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a remote user to degrade federation functionality.
The vulnerability exists due to improper validation of specified type of input in device key validation when processing device keys. A remote user can register and use invalid device keys to degrade federation functionality.
The issue can unpredictably break outbound federation to other homeservers.
Remediation
Install update from vendor's website.