CVE-2026-112021
highsnac2 before 2.93 contains a heap-based buffer overflow vulnerability in _xs_json_load_lexer() that allows unauthenticated remote attackers to corrupt heap mem…
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Affected products
Not reported by the source (unknown — not "none").
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
No vendor advisory or patch reference tagged by NVD. Check the references below.
References
- https://codeberg.org/grunfink/snac2 disclosure@vulncheck.com
- https://codeberg.org/grunfink/snac2/commit/ec2c5c2046e0381bc942ec5d0d05ec861fe377e7 disclosure@vulncheck.com
- https://codeberg.org/grunfink/snac2/releases/tag/2.93 disclosure@vulncheck.com
- https://codeberg.org/grunfink/snac2/src/tag/2.92/xs_json.h#L283-L285 disclosure@vulncheck.com
- https://gist.github.com/nullenvk/2bf288e2d34cb3d4b7143e61dbf7d90b disclosure@vulncheck.com
- https://nullenvk.pl/posts/02-snac2-json disclosure@vulncheck.com
- https://www.vulncheck.com/advisories/snac2-before-2.93-heap-based-buffer-overflow-via-json... disclosure@vulncheck.com