CVE-2026-112021
snac2 before 2.93 contains a heap-based buffer overflow vulnerability in _xs_json_load_lexer() that…
- Risk score
- 60/100
- CVSS
- 7.5 v3.1
- Exploit chance (30 days)
- 0.7%
- Published
- 18 Oct 2026
Open in the live forecast Today's forecast
What to know
- What it is
- 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 …
- Affected
- See advisory
- Fix
- Upgrade the product to 2.93 or later.
- Exploitation
- No known exploitation
Why it is Amber
- CVSS 7.5 high
- Remotely exploitable without logging in
References
- https://codeberg.org/grunfink/snac2
- https://codeberg.org/grunfink/snac2/commit/ec2c5c2046e0381bc942ec5d0d05ec861fe377e7
- https://codeberg.org/grunfink/snac2/releases/tag/2.93
- https://codeberg.org/grunfink/snac2/src/tag/2.92/xs_json.h#L283-L285
- https://gist.github.com/nullenvk/2bf288e2d34cb3d4b7143e61dbf7d90b
- https://nullenvk.pl/posts/02-snac2-json
- https://www.vulncheck.com/advisories/snac2-before-2.93-heap-based-buffer-overflow-via-json-parser-xs-json-load-lexer
Original 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.
Last activity 18 Oct 2026. Patch Forecast updates every hour.