CVE-2026-39863 | 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.

Published: 2026-04-08 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-39863 is rated Moderate Risk (42.9/100): CVSS High severity, with low exploitation likelihood (EPSS 0.45%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-39863

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.04% 0.45% +0.41%
2 2026-04-21 0.11% 0.04% -0.06%
3 2026-04-09 — 0.11% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-39863

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2026-39863

OS Trackers for CVE-2026-39863

vendor priority summary link
alpine — CVE-2026-39863: 1 source package rows (kamailio); 5 state rows across 5 repos (3.20-main, 3.21-main, 3.22-main, 3.23-main, edge-main); fixed 5, open 0. https://security.alpinelinux.org/vuln/CVE-2026-39863
debian not yet assigned CVE-2026-39863 not yet assigned priority: Debian including 1 source packages (kamailio), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. https://security-tracker.debian.org/tracker/CVE-2026-39863
ubuntu medium CVE-2026-39863 medium priority: Ubuntu including 1 source packages (kamailio), 7 status rows across 7 suites (bionic, focal, jammy, noble, questing, upstream, xenial): needs-triage 6, released 1. https://ubuntu.com/security/CVE-2026-39863

Affected software / configurations for CVE-2026-39863

Vendor Product Version Raw CPE
kamailio kamailio < 5.8.8 cpe:2.3:a:kamailio:kamailio:*:*:*:*:*:*:*:*
kamailio kamailio >= 6.0.0, < 6.0.6 cpe:2.3:a:kamailio:kamailio:*:*:*:*:*:*:*:*
kamailio kamailio 6.1.0 cpe:2.3:a:kamailio:kamailio:6.1.0:*:*:*:*:*:*:*

References for CVE-2026-39863

cvelogic Threat Intelligence