CVE-2026-112021
snac2 before 2.93 Heap-Based Buffer Overflow via JSON Parser _xs_json_load_lexer()
grunfink snac2
CVSS
8.7HighExploitationPublic exploit codeCISA's assessment says proof of concept code is public, assessed 19 Oct 2026. Not in the KEV catalogCISA via CVE List
Exploit odds (EPSS)0.67%Chance of exploitation activity in the next 30 days, higher than 51% of CVEs. Scored 23 Oct 2026FIRST EPSS
What fixes it
- 2.93snac2CVE List
A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.
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.
Text from CVE List
Affected versions 1
- snac2affected: all versions before 2.93CVE List
References 7
- codeberg.org/grunfink/snac2/commit/ec2c5c2046e0381bc942ec5d0d05ec861fe377e7Fixvia CVE List
- codeberg.org/grunfink/snac2/releases/tag/2.93Fixvia CVE List
- vulncheck.com/advisories/snac2-before-2.93-heap-based-buffer-overflow-via-json-parser-xs-json-load-lexerAdvisoryvia CVE List
- gist.github.com/nullenvk/2bf288e2d34cb3d4b7143e61dbf7d90bExploitvia CVE List
- nullenvk.pl/posts/02-snac2-jsonReferencevia CVE List
- codeberg.org/grunfink/snac2/src/tag/2.92/xs_json.h#L283-L285Referencevia CVE List
- codeberg.org/grunfink/snac2Referencevia CVE List