CVE-2026-112021 snac2 before 2.93 Heap-Based Buffer Overflow via JSON Parser _xs_json_load_lexer()
Unauthenticated remote attackers can cause heap corruption and server crashes via crafted JSON payloads in snac2, potentially leading to code execution.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-112021?
CVE-2026-112021 is a high-severity memory corruption vulnerability in grunfink snac2, published on 18 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
snac2 before 2.93 contains a heap-based buffer overflow vulnerability in _xs_json_load_lexer() that allows unauthenticated remote attackers to corrupt heap memory by sending JSON strings containing a \u0000 escape. Attackers can send a single crafted application/activity+json POST to activitypub_post_handler(), which parses it before signature checks, overflowing heap allocations and crashing the server.
Weakness: CWE-122
Which versions are affected by CVE-2026-112021?
How do I fix CVE-2026-112021?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-112021 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-112021 exists.
Sources
Also known as DEBIAN-CVE-2026-112021, GHSA-6hv3-2r7g-774j, UBUNTU-CVE-2026-112021.