CVEvulnerability
CVE-2026-112021
8.7 HIGH
Official page ↗
- Status
- Deferred
- Published
- 2026-10-18
- Last modified
- 2026-10-19
- Assigner
- [email protected]
- CVSS 4.0 ([email protected])
- 8.7 HIGH — CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- CVSS 3.1 ([email protected])
- 7.5 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weaknesses
- CWE-122
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.
Related
Weakness · CWE (1)
- CWE-122 Heap-based Buffer Overflow weakness
References
- https://codeberg.org/grunfink/snac2 codeberg.org
- https://codeberg.org/grunfink/snac2/commit/ec2c5c2046e0381bc942ec5d0d05ec861fe377e7 codeberg.org
- https://codeberg.org/grunfink/snac2/releases/tag/2.93 codeberg.org
- https://codeberg.org/grunfink/snac2/src/tag/2.92/xs_json.h#L283-L285 codeberg.org
- https://gist.github.com/nullenvk/2bf288e2d34cb3d4b7143e61dbf7d90b gist.github.com
- https://nullenvk.pl/posts/02-snac2-json nullenvk.pl
- https://www.vulncheck.com/advisories/snac2-before-2.93-heap-based-buffer-overflow-via-json-parser-xs-json-load-lexer www.vulncheck.com