CVE-2026-28799 PJSIP: Heap use-after-free in PJSIP presence subscription termination handler
A heap use-after-free in PJSIP's presence subscription handler allows attackers to potentially execute code or cause denial of service via crafted unsubscription requests.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-28799?
CVE-2026-28799 is a high-severity use after free vulnerability in pjsip pjproject, published on 6 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
PJSIP is a free and open source multimedia communication library written in C. Prior to version 2.17, a heap use-after-free vulnerability exists in PJSIP's event subscription framework (evsub.c) that is triggered during presence unsubscription (SUBSCRIBE with Expires=0). This issue has been patched in version 2.17.
Weakness: CWE-416
Which versions are affected by CVE-2026-28799?
It affects 1 product.
Products include Pjsip Pjsip.
How do I fix CVE-2026-28799?
Upgrade to a fixed version.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-28799 being exploited?
There is no known exploitation of CVE-2026-28799 in the wild and no public exploit code.
Other vulnerabilities in pjsip pjproject
- CVE-2026-29068 PJSIP: Stack buffer overflow in Opus codec parser
- CVE-2026-40614 PJSIP: Heap buffer overflow in Opus codec decoding
- CVE-2026-32945 PJSIP is vulnerable to Heap-based Buffer Overflow through DNS parser
- CVE-2026-40892 PJSIP: Stack buffer overflow in pjsip_auth_create_digest2()
- CVE-2026-26967 PJSIP has a Heap-based Buffer Overflow vulnerability in its H.264 unpacketizer
Sources
Also known as ALPINE-CVE-2026-28799, DEBIAN-CVE-2026-28799, GHSA-8fj4-fv9f-hjpc, UBUNTU-CVE-2026-28799.