{"id":"CVE-2026-112021","title":"snac2 before 2.93 Heap-Based Buffer Overflow via JSON Parser _xs_json_load_lexer()","summary":"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 s…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cvssSource":"cna","cwe":["CWE-122"],"vendor":"grunfink","product":"snac2","affected":["snac2 < 2.93"],"ssvc":{"exploitation":"poc","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-19T16:04:19.806894Z"},"exploitAvailable":true,"published":"2026-10-18","updated":"2026-10-19","sourceUpdated":"2026-10-19T16:05:15.544Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-112021","references":[{"url":"https://nullenvk.pl/posts/02-snac2-json"},{"url":"https://gist.github.com/nullenvk/2bf288e2d34cb3d4b7143e61dbf7d90b"},{"url":"https://codeberg.org/grunfink/snac2/src/tag/2.92/xs_json.h#L283-L285"},{"url":"https://codeberg.org/grunfink/snac2/commit/ec2c5c2046e0381bc942ec5d0d05ec861fe377e7"},{"url":"https://codeberg.org/grunfink/snac2/releases/tag/2.93"},{"url":"https://codeberg.org/grunfink/snac2"},{"url":"https://www.vulncheck.com/advisories/snac2-before-2.93-heap-based-buffer-overflow-via-json-parser-xs-json-load-lexer","label":"VulnCheck Advisory: snac2 before 2.93 Heap-Based Buffer Overflow via JSON Parser _xs_json_load_lexer()"}],"tags":["cve.org","exploit-available"],"epss":0.0067,"epssPercentile":0.5178,"ingestedAt":"2026-10-18T11:40:26.618Z","slug":"CVE-2026-112021","body":"## Overview\n\nsnac2 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.\n\n## Affected\n\n- `snac2 < 2.93`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"midnight","depthScore":53,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[{"seq":225012,"id":"CVE-2026-112021","ts":1792427589129,"field":"exploit_available","old":"false","new":"true"}]}