The vulnerability is an out-of-bounds read that occurs in the multipart body parser of OpenSIPS. While parsing a SIP message that contains a MIME boundary in a multipart/mixed body, the find_line_delimiter() function uses strncmp() to compare delimiter length bytes starting beyond the logical end of the body buffer. The flaw can cause the server to read memory past the buffer, potentially exposing sensitive data stored there. The impact is limited to confidentiality risk and is reflected in a CVSS score of 5.3.

OpenSIPS servers running a version earlier than 3.6.6 or before the release of 4.0.0‑rc1 are affected. The issue only affects the OpenSIPS project itself; no other vendors or products are listed.

The exploit requires delivery of a specially crafted SIP packet containing a Content‑Type of multipart/mixed with a boundary parameter whose body ends two to three bytes before the final boundary separator. An attacker can then trigger the out‑of‑bounds read over the network. No privilege escalation or code execution is provided. The EPSS score is not available, the CVSS score of 5.3 positions the risk as moderate, and the vulnerability is not listed in the CISA KEV catalog.