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Vulnerability Analysis
OpenSIPS: Denial of Service in watcherinfo XML generation from oversized watcher URI

CVE-2026-45809

OpenSIPS is a Session Initiation Protocol (SIP) server implementation. Versions prior to 3.6.6 and 4.0.0-rc1 contain a denial of service vulnerability in the watcherinfo generation functionality. An attacker can create an oversized watcher entry by sending a SUBSCRIBE Event: presence request with a long From URI, and then trigger presence.winfo watcherinfo XML generation for the same presentity. OpenSIPS copies the stored watcher URI into a fixed-size stack buffer, overflowing it and crashing the process. A remote attacker can crash an OpenSIPS worker in deployments that expose handle_subscribe() and allow watcherinfo (presence.winfo) generation. The issue is configuration-dependent because the presence and presence_xml modules must be loaded and SUBSCRIBE routing must be reachable. This issue has been fixed in versions 3.6.6 and 4.0.0-rc1.

No Active Exploit Signals
CVSS Base Score
8.7
HIGH
Exploitability:-
Impact Score:-
Temporal Score:-
EPSS:0.39%

Threat Intelligence Signals

CISA KEV
No
KEV Date Added
Ransomware Use
KEV Due Date
VulnCheck In-the-Wild
No
Nuclei Template
No
EPSS Score
0.388%
EPSS Percentile
31.5th pct
GHSA ID
GitHub Severity
SSVC Exploitation
Proof of Concept
SSVC Automatable
Yes
Vulnerability Class

Identity & Timeline

Status-
Assigning Authority-
CVSS Version / Source-
Reserved-
Published-
Patch Date (date_public)-
Exploit DB Date-
First GitHub PoC Date-
Last Updated-
Time to Patch (Days to fix)-
Exploit Release Gap-
PoC Release Gap-
Exploit DB ReferencesNone identified

Affected Products & Versions

Vendor Product Affected Versions
No affected products specified.

References

No reference links found.

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