Out-of-bounds Read in Kamailio

CVE-2026-39864

Kamailio is an open source implementation of a SIP Signaling Server. Prior to 6.0.5 and 5.8.7, an out-of-bounds read in the auth module of Kamailio (formerly OpenSER and SER) allows remote attackers to cause a denial of service (process crash) via a specially crafted SIP packet if a successful user authentication without a database backend is followed by additional user identity checks. This vulnerability is fixed in 6.0.5 and 5.8.7.

Vulnerability class: Buffer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 4.4 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.005 (43.4th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 43rd percentile — 43.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-39864: held from 0.003 to 0.005.

EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002

Affected products

  • Kamailio — versions < 5.8.7, >= 6.0.0, < 6.0.5

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-39864?
CVE-2026-39864 is a medium-severity vulnerability in Kamailio, classified under Out-of-bounds Read. CVSS score: 4.4/10. Published 2026-04-08.
How severe is CVE-2026-39864?
Medium severity. CVSS v3 base score is 4.4 out of 10.