CVE-2026-45809

Name of the Vulnerable Software and Affected Versions OpenSIPS versions prior to 3.6.6 OpenSIPS versions prior to 4.0.0-rc1

Description A denial of service issue exists in the watcherinfo generation functionality. A remote attacker can crash an OpenSIPS worker by sending a SUBSCRIBE Event: presence request containing a long From URI to create an oversized watcher entry, and subsequently triggering the presence.winfo watcherinfo XML generation for the same presentity. The crash occurs because the software copies the stored watcher URI into a fixed-size stack buffer, leading to a buffer overflow. This issue is configuration-dependent, requiring the presence and presence xml modules to be loaded and the handle subscribe() function to be exposed and reachable via SUBSCRIBE routing.

Recommendations Update to version 3.6.6. Update to version 4.0.0-rc1. As a temporary mitigation, restrict access to the handle subscribe() function or avoid loading the presence and presence xml modules if they are not required.