CVE-2026-112021
snac2 before 2.93 Heap-Based Buffer Overflow via JSON Parser _xs_json_load_lexer()
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-122 |
| Vendor | grunfink |
| Product | snac2 |
| Published | Oct 18, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
grunfink / snac2
0 < 2.93
References
nullenvk.pl: https://nullenvk.pl/posts/02-snac2-json gist.github.com: https://gist.github.com/nullenvk/2bf288e2d34cb3d4b7143e61dbf7d90b codeberg.org: https://codeberg.org/grunfink/snac2/src/tag/2.92/xs_json.h#L283-L285 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 vulncheck.com: https://www.vulncheck.com/advisories/snac2-before-2.93-heap-based-buffer-overflow-via-json-parser-xs-json-load-lexer
Credits
nullenvk