High 7.5Published Oct 18, 2026

CVE-2026-112021snac2 before 2.93 Heap-Based Buffer Overflow via JSON Parser _xs_json_load_lexer()

Updated under an hour ago (Oct 28, 2026, 4:30 PM ET)

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It affects grunfink snac2. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.67%, higher than 52% of scored CVEs.

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Every CVE for grunfink snac2

Exploited in the last 30 days

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: 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-122
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.67% (percentile 52)
Assigned by: VulnCheck
NVD analysis: Deferred
Record last updated: Oct 19, 2026
First seen by InfoSec Signals: Oct 18, 2026

Affected products

Affected products

grunfink snac2 grunfink:snac2 (from the name)	before 2.93	CNA record

References

References

https://nullenvk.pl/posts/02-snac2-json	technical-description
https://gist.github.com/nullenvk/2bf288e2d34cb3d4b7143e61dbf7d90b	exploit
https://codeberg.org/grunfink/snac2/src/tag/2.92/xs_json.h#L283-L285	technical-description
https://codeberg.org/grunfink/snac2/commit/ec2c5c2046e0381bc942ec5d0d05ec861fe377e7	patch
https://codeberg.org/grunfink/snac2/releases/tag/2.93	release-notes
https://codeberg.org/grunfink/snac2	product
https://www.vulncheck.com/advisories/snac2-before-2.93-heap-based-buffer-overflow-via-json-parser-xs-json-load-lexer	third-party-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.