# CVE-2026-39863: Kamailio out-of-bounds access in core TCP processing

Source: https://junglewise.ai/threats/cve-2026-39863-kamailio-out-of-bounds-access-in-core-tcp-processing  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-08. Updated: 2026-07-24  
License: CC BY 4.0 with a link back

CVE-2026-39863 · Severity: high · CVSS 7.5 · Published 2026-04-08

Kamailio is an open-source server used for managing internet-based phone calls and messaging (SIP signaling). A vulnerability has been identified where a remote attacker can send a malicious data packet to the server, causing it to crash. This results in a denial of service, potentially disrupting communication services for all users until the system is restored.

Vendors: [Kamailio](https://junglewise.ai/threats/vendors/kamailio).

## Quick answers

**Is CVE-2026-39863 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-39863 being exploited in the wild.

**How severe is CVE-2026-39863?** High severity, with a CVSS score of 7.5, published 8 April 2026.

**Which products and versions are affected?** Kamailio SIP Server < 5.8.8, 6.0.0 to < 6.0.6, 6.1.0 to < 6.1.1.

**Is there a fix for CVE-2026-39863?** A patch was published on 2026-04-08: Fixes available in versions 5.8.8, 6.0.6, and 6.1.1 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-39863 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-39863?** Check whether you run Kamailio SIP Server at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An out-of-bounds access vulnerability (CWE-119) exists in the core TCP data processing component of Kamailio. The flaw is triggered when the server processes a specially crafted data packet sent over a TCP or TLS connection. A remote, unauthenticated attacker can exploit this to cause a process crash, leading to a denial of service (DoS). The vulnerability affects Kamailio instances configured with TCP or TLS listeners. Patches have been released in versions 5.8.8, 6.0.6, and 6.1.1 to address the improper restriction of operations within memory buffer bounds.

## Affected products

- Kamailio Kamailio SIP Server < 5.8.8, 6.0.0 to < 6.0.6, 6.1.0 to < 6.1.1

## Timeline

- 2026-04-07: advisory: GitHub Security Advisory published by vendor
- 2026-04-08: disclosed: CVE published to NVD
- 2026-04-08: patched: Fixes available in versions 5.8.8, 6.0.6, and 6.1.1

## References

- [https://github.com/kamailio/kamailio/security/advisories/GHSA-2wj4-f825-2h2f](https://github.com/kamailio/kamailio/security/advisories/GHSA-2wj4-f825-2h2f)