# CVE-2026-52022: Kamailio IMS P-CSCF denial of service in REGISTER handling

Source: https://junglewise.ai/threats/cve-2026-52022-kamailio-ims-p-cscf-denial-of-service-in-register-handling  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-01. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-52022 · Severity: high · CVSS 7.5 · Published 2026-09-01

Kamailio is a widely-used SIP server that handles voice and messaging registration in telecommunications networks. A vulnerability in its IMS P-CSCF (Proxy Call Session Control Function) component causes the server to crash when processing malformed or rapidly-sequenced SIP REGISTER messages during device registration. An attacker can exploit this to take down the registration service, preventing legitimate devices from connecting to the network.

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

## Quick answers

**Is CVE-2026-52022 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-52022 being exploited in the wild.

**How severe is CVE-2026-52022?** High severity, with a CVSS score of 7.5, published 1 September 2026.

**Which products and versions are affected?** Kamailio 6.1.1 and before.

**Is there a fix for CVE-2026-52022?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-52022 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-52022?** Check whether you run Kamailio 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

The vulnerability is a use-after-free / double-free memory corruption issue in the ims_usrloc_pcscf module's REGISTER reply handling path, specifically during IPSec negotiation in the free_security() function. The defect occurs when overlapping or high-rate registration transactions trigger abnormal state handling in the IMS contact management code. The attack is network-accessible and requires no authentication; an attacker can send specially crafted or high-frequency SIP REGISTER messages to induce a segmentation fault (SIGSEGV) in the P-CSCF worker process. The root cause is a missing check to prevent double memory free when certain transaction states coincide. A fix has been released via commit 91c5ca7, which adds checks in the free_security() method to prevent the double-free condition.

## Affected products

- Kamailio Kamailio 6.1.1 and before

## Timeline

- 2026-09-01: disclosed
- other: Double-free bug fixed in commit 91c5ca7

## References

- [https://github.com/kamailio/kamailio/commit/91c5ca751799db4f25a28a495350cc97f7c2f390](https://github.com/kamailio/kamailio/commit/91c5ca751799db4f25a28a495350cc97f7c2f390)
- [https://github.com/kamailio/kamailio/issues/4670](https://github.com/kamailio/kamailio/issues/4670)

## Related threats

- [Kamailio stack buffer overflow in ims_qos_npn module](https://junglewise.ai/threats/cve-2026-106804-a-stack-based-buffer-overflow-exists-in-kamailio-v6-1-3-and-v6-1)
- [Kamailio stack buffer overflow in ims_registrar_pcscf module](https://junglewise.ai/threats/cve-2026-106803-a-stack-based-buffer-overflow-exists-in-kamailio-v6-1-3-and-v6-1)
- [Kamailio sipt module buffer overflow in ISUP parser](https://junglewise.ai/threats/cve-2026-108822-a-vulnerability-was-detected-in-kamailio-up-to-6-0-7-6-1-3-the)
- [Kamailio heap buffer overflow in CDP Diameter Receiver](https://junglewise.ai/threats/cve-2026-93962-a-weakness-has-been-identified-in-kamailio-up-to-5-8-8-6-0-7-6-1)
- [Kamailio ims_registrar_pcscf double free in security agreement parsing](https://junglewise.ai/threats/cve-2026-52023-kamailio-ims-registrar-pcscf-double-free-in-security-agreement)