What is CVE-2026-39863?

CVE-2026-39863 is a high-severity vulnerability in Kamailio, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 7.5/10. Published 2026-04-08.

How severe is CVE-2026-39863?

High severity. CVSS v3 base score is 7.5 out of 10.

Buffer overflow in Kamailio

CVE-2026-39863

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.

Vulnerability class: Buffer Overflow

EPSS: 0.005 (37.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Kamailio — versions < 5.8.8, 6.1.0, >= 6.1.0, < 6.1.1

Weakness classification (CWE)

CWE-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer

References

security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)

Frequently asked questions

What is CVE-2026-39863?: CVE-2026-39863 is a high-severity vulnerability in Kamailio, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 7.5/10. Published 2026-04-08.
How severe is CVE-2026-39863?: High severity. CVSS v3 base score is 7.5 out of 10.