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CVE-2026-39863

Kamailio Core: TCP Data Processing Vulnerability

7.5 HighFix available

Kamailio is an open source implementation of a SIP Signaling Server. Prior to 6.1.1, 6.0.6, and 5.8.8, an out-of-bounds access in the core of Kamailio (formerly OpenSER and SER) allows remote attackers to cause a denial of service (process crash) via a specially crafted data packet sent over TCP. The issue impacts Kamailio instances having TCP or TLS listeners. This vulnerability is fixed in 5.1.1, 6.0.6, and 5.8.8.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.47%Up 0.4 points since Apr 9, 2026
90%50%10%1%

What each source reports

CVE List Score used 7.5

Kamailio Core: TCP Data Processing Vulnerability

Kamailio is an open source implementation of a SIP Signaling Server. Prior to 6.1.1, 6.0.6, and 5.8.8, an out-of-bounds access in the core of Kamailio (formerly OpenSER and SER) allows remote attackers to cause a denial of service (process crash) via a specially crafted data packet sent over TCP. The issue impacts Kamailio instances having TCP or TLS listeners. This vulnerability is fixed in 5.1.1, 6.0.6, and 5.8.8.

Record
CVE-2026-39863
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-119
Updated
2026-11-02
EUVDEUVD-2026-20616 7.5

Kamailio is an open source implementation of a SIP Signaling Server. Prior to 6.1.1, 6.0.6, and 5.8.8, an out-of-bounds access in the core of Kamailio (formerly OpenSER and SER) allows remote attackers to cause a denial of service (process crash) via a specially crafted data packet sent over TCP. The issue impacts Kamailio instances having TCP or TLS listeners. This vulnerability is fixed in 5.1.1, 6.0.6, and 5.8.8.

Record
EUVD-2026-20616
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
NVD 7.5

Kamailio is an open source implementation of a SIP Signaling Server. Prior to 6.1.1, 6.0.6, and 5.8.8, an out-of-bounds access in the core of Kamailio (formerly OpenSER and SER) allows remote attackers to cause a denial of service (process crash) via a specially crafted data packet sent over TCP. The issue impacts Kamailio instances having TCP or TLS listeners. This vulnerability is fixed in 5.1.1, 6.0.6, and 5.8.8.

Record
CVE-2026-39863
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-119
Updated
2026-11-02
OSVALPINE-CVE-2026-39863 7.5

Kamailio is an open source implementation of a SIP Signaling Server. Prior to 6.1.1, 6.0.6, and 5.8.8, an out-of-bounds access in the core of Kamailio (formerly OpenSER and SER) allows remote attackers to cause a denial of service (process crash) via a specially crafted data packet sent over TCP. The issue impacts Kamailio instances having TCP or TLS listeners. This vulnerability is fixed in 5.1.1, 6.0.6, and 5.8.8.

Record
ALPINE-CVE-2026-39863
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSV 7.5

Kamailio Core: TCP Data Processing Vulnerability

Kamailio is an open source implementation of a SIP Signaling Server. Prior to 6.1.1, 6.0.6, and 5.8.8, an out-of-bounds access in the core of Kamailio (formerly OpenSER and SER) allows remote attackers to cause a denial of service (process crash) via a specially crafted data packet sent over TCP. The issue impacts Kamailio instances having TCP or TLS listeners. This vulnerability is fixed in 5.1.1, 6.0.6, and 5.8.8.

Record
CVE-2026-39863
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-119
Updated
2026-11-02
OSVDEBIAN-CVE-2026-39863 7.5

Kamailio is an open source implementation of a SIP Signaling Server. Prior to 6.1.1, 6.0.6, and 5.8.8, an out-of-bounds access in the core of Kamailio (formerly OpenSER and SER) allows remote attackers to cause a denial of service (process crash) via a specially crafted data packet sent over TCP. The issue impacts Kamailio instances having TCP or TLS listeners. This vulnerability is fixed in 5.1.1, 6.0.6, and 5.8.8.

Record
DEBIAN-CVE-2026-39863
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2026-39863 7.5

Kamailio is an open source implementation of a SIP Signaling Server. Prior to 6.1.1, 6.0.6, and 5.8.8, an out-of-bounds access in the core of Kamailio (formerly OpenSER and SER) allows remote attackers to cause a denial of service (process crash) via a specially crafted data packet sent over TCP. The issue impacts Kamailio instances having TCP or TLS listeners. This vulnerability is fixed in 5.1.1, 6.0.6, and 5.8.8.

Record
UBUNTU-CVE-2026-39863
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
kamailio
Alpine:v3.14
 6.0.0 up to 5.4.5-r2
5.4.5-r2
kamailio
Alpine:v3.20
 6.0.0 up to 5.8.8-r0
5.8.8-r0
kamailio
Alpine:v3.21
 6.0.0 up to 5.8.8-r0
5.8.8-r0
kamailio
Alpine:v3.22
 6.0.0 up to 6.0.6-r0
6.0.6-r0
kamailio
Alpine:v3.23
 6.0.0 up to 6.0.6-r0
6.0.6-r0
kamailio
Alpine:v3.24
 6.0.0 up to 6.0.6-r0
6.0.6-r0
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 6.1.1-2, plus listed versions
6.0.1-16.0.2-16.0.2-26.0.2-36.0.3-1
Show 4 moreShow less
6.0.3-26.0.3-36.0.4-16.0.5-1
6.1.1-2
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
Show 7 moreShow less
Affected packages
PackageAffectedFixed
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
kamailio
Ubuntu:26.10
 All versions, plus listed versions
6.0.5-1ubuntu16.1.2-1ubuntu26.1.2-1ubuntu36.1.2-1ubuntu4
 None known
kamailio
Ubuntu:26.04:LTS
 All versions, plus listed versions
6.0.2-26.0.5-16.0.5-1build16.0.5-1ubuntu1
 None known

History

History
RecordedChangedSources
first indexedCVE List, EUVD, NVD, OSV

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

In short

CVE-2026-39863 is a high vulnerability (CVSS 7.5) in Kamailio, published April 8, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.47%, the 41st percentile. Fixed in kamailio 5.4.5-r2.

References

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