CVE-2026-45705 OpenSIPS CVE debrief

Who should care

OpenSIPS users and administrators, SIP server operators, and security teams responsible for VoIP infrastructure should be aware of this vulnerability and take steps to mitigate it. This includes reviewing and updating Content-Type handling in SIP configurations, monitoring for suspicious SIP traffic patterns, and applying patches or upgrading to a fixed version. Security teams should also review compensating controls for exposed systems while remediation is scheduled and verified.

Technical summary

OpenSIPS versions prior to 3.6.6 and 4.0.0-rc1 have a vulnerability in the find_line_delimiter() function of the multipart body parser. When processing SIP messages with Content-Type: multipart/mixed and a boundary parameter, the function can perform an out-of-bounds read via strncmp() if a -- pattern is near the end of the body without being followed by the actual boundary delimiter. This issue can lead to crashes or potential data exposure. Affected OpenSIPS users should prioritize patching to prevent potential crashes or data exposure via SIP messages with malicious multipart/mixed Content-Type headers.

Defensive priority

OpenSIPS users should prioritize patching to prevent potential crashes or data exposure via SIP messages with malicious multipart/mixed Content-Type headers.

Recommended defensive actions

• Inventory OpenSIPS installations and verify versions are 3.6.6 or 4.0.0-rc1 or later
• Apply patches or upgrade to a fixed version
• Monitor for suspicious SIP traffic patterns
• Review and update Content-Type handling in SIP configurations
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The find_line_delimiter() function in OpenSIPS performs an out-of-bounds read when searching for MIME boundary delimiters in SIP messages with Content-Type: multipart/mixed. This occurs when a -- pattern is near the end of the body without being followed by the actual boundary delimiter. Evidence is based on OpenSIPS and NVD information. Further verification is recommended to assess affected scope and potential impact.

Official resources