# CVE-2026-52023: Kamailio ims_registrar_pcscf double free in security agreement parsing

Source: https://junglewise.ai/threats/cve-2026-52023-kamailio-ims-registrar-pcscf-double-free-in-security-agreement  
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-2026-52023 · Severity: high · CVSS 7.5 · Published 2026-09-01

Kamailio is an open-source SIP server used to route voice and video calls in telecom networks. A flaw in the IMS P-CSCF module allows a remote attacker to crash the service by sending concurrent registration and de-registration requests, causing a memory corruption issue that terminates worker processes. This disrupts call processing for affected users.

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

## Quick answers

**Is CVE-2026-52023 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-52023 being exploited in the wild.

**How severe is CVE-2026-52023?** 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-2026-52023?** A patch was published on 2026-09-01: Fix available in commit 722c06b Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-52023 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-52023?** 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 double-free memory corruption bug in the ims_registrar_pcscf module, specifically in the sec_agree.c:parse_sec_agree() function that handles security-agreement parsing. The flaw occurs when concurrent REGISTER and de-REGISTER requests for the same contact are processed simultaneously; one execution path continues handling security-agreement state while another updates or expires the pending registration, leading to inconsistent internal state and a double memory free. The attack requires network access to the SIP server and no authentication is needed—an unauthenticated attacker can send overlapping registration requests with varying expiry times to trigger a crash. The issue has been fixed in the Kamailio repository (commit 722c06b) by preventing the double free condition.

## Affected products

- Kamailio Kamailio 6.1.1 and before

## Timeline

- 2026-09-01: disclosed
- 2026-09-01: patched: Fix available in commit 722c06b

## References

- [https://github.com/kamailio/kamailio/commit/722c06b3efc53ccb369ce812c685c7d069508187](https://github.com/kamailio/kamailio/commit/722c06b3efc53ccb369ce812c685c7d069508187)
- [https://github.com/kamailio/kamailio/issues/4671](https://github.com/kamailio/kamailio/issues/4671)

## 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 P-CSCF denial of service in REGISTER handling](https://junglewise.ai/threats/cve-2026-52022-kamailio-ims-p-cscf-denial-of-service-in-register-handling)