CVE-2026-39864

Kamailio Auth: Processing Vulnerability For Additional Authenticated User Identity Checks

4.4 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: High
Privileges needed: High
User interaction: None

What an attacker can affect

Confidentiality: None
Integrity: None
Availability: High

Exploit likelihood

0.31%Up 0.1 points since Apr 9, 2026

What each source reports

CVE List Score used 4.4

Kamailio Auth: Processing Vulnerability For Additional Authenticated User Identity Checks

Record: CVE-2026-39864
CVSS 3.1: 4.4 MediumCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-125
Updated: 2026-11-02

EUVDEUVD-2026-20617 4.4

Record: EUVD-2026-20617
CVSS 3.1: 4.4 MediumCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

NVD 4.4

Record: CVE-2026-39864
CVSS 3.1: 4.4 MediumCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
CVSS 3.1: 4.9 MediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-125
Updated: 2026-11-02

OSV 4.4

Kamailio Auth: Processing Vulnerability For Additional Authenticated User Identity Checks

Record: CVE-2026-39864
CVSS 3.1: 4.4 MediumCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-125
Updated: 2026-11-02

OSVDEBIAN-CVE-2026-39864 4.9

Record: DEBIAN-CVE-2026-39864
CVSS 3.1: 4.9 MediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVUBUNTU-CVE-2026-39864 4.4

Record: UBUNTU-CVE-2026-39864
CVSS 3.1: 4.4 MediumCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
CVSS 3.1: 4.9 MediumCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

Affected products

kamailio

Affected packages

Affected packages
Package	Affected	Fixed
`kamailio` Debian:12	All versions, plus listed versions 5.6.3-25.6.4-15.7.0-15.7.2-15.7.3-1 Show 23 moreShow less 5.7.4-15.8.2-25.8.2-35.8.2-45.8.3-15.8.4-15.8.5-16.0.0-16.0.1-16.0.2-16.0.2-26.0.2-36.0.3-16.0.3-26.0.3-36.0.4-16.0.5-16.1.1-26.1.1-2.16.1.2-16.1.3-16.1.3-26.1.4-1	None known
`kamailio` Debian:13	before 6.0.1-1+deb13u2, plus listed versions 6.0.1-16.0.1-1+deb13u1	6.0.1-1+deb13u2
`kamailio` Debian:14	before 6.0.5-1, plus listed versions 6.0.1-16.0.2-16.0.2-26.0.2-36.0.3-16.0.3-26.0.3-36.0.4-1	6.0.5-1
`kamailio` Ubuntu:Pro:16.04:LTS	All versions, plus listed versions 4.3.1-2ubuntu14.3.4-1.1ubuntu14.3.4-1.1ubuntu24.3.4-1.1ubuntu2.14.3.4-1.1ubuntu2.1+esm14.3.4-1.1ubuntu2.1+esm2	None known
`kamailio` Ubuntu:Pro:18.04:LTS	All versions, plus listed versions 4.4.2-3ubuntu55.0.4-1ubuntu15.1.1-1ubuntu15.1.1-1ubuntu45.1.2-1ubuntu15.1.2-1ubuntu25.1.2-1ubuntu2+esm15.1.2-1ubuntu2+esm2	None known
`kamailio` Ubuntu:Pro:20.04:LTS	All versions, plus listed versions 5.2.3-1build35.2.3-1build45.3.0-25.3.1-15.3.2-1build1 Show 4 moreShow less 5.3.2-1build25.3.2-1build35.3.2-1ubuntu0.1~esm15.3.2-1ubuntu0.1~esm2	None known
`kamailio` Ubuntu:22.04:LTS	All versions, plus listed versions 5.4.4-1build15.4.4-1ubuntu15.4.4-1ubuntu25.5.4-1	None known
`kamailio` Ubuntu:24.04:LTS	All versions, plus listed versions 5.7.0-1build15.7.2-1build15.7.3-15.7.4-15.7.4-1build15.7.4-1build55.7.4-1build7	None known
`kamailio` Ubuntu:25.10	All versions, plus listed versions 5.8.4-1build16.0.1-1build26.0.2-2	None known

History

History
Recorded	Changed	Sources
Nov 2, 2026	first indexed	CVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-39864 is a medium vulnerability (CVSS 4.4) in Kamailio, published April 8, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.31%, the 24th percentile. Fixed in kamailio 6.0.1-1+deb13u2.