CVE-2026-112021

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 v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://codeberg.org/grunfink/snac2
https://codeberg.org/grunfink/snac2/commit/ec2c5c2046e0381bc942ec5d0d05ec861fe377e7
https://codeberg.org/grunfink/snac2/releases/tag/2.93
https://codeberg.org/grunfink/snac2/src/tag/2.92/xs_json.h#L283-L285
https://gist.github.com/nullenvk/2bf288e2d34cb3d4b7143e61dbf7d90b
https://nullenvk.pl/posts/02-snac2-json
https://www.vulncheck.com/advisories/snac2-before-2.93-heap-based-buffer-overflow-via-json-parser-xs-json-load-lexer

Configurations

No configuration.

History

18 Oct 2026, 12:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-18 12:17

Updated : 2026-10-19 21:14

NVD link : CVE-2026-112021

Mitre link : CVE-2026-112021

CVE.ORG link : CVE-2026-112021

JSON object : View

Products Affected

No product.

CWE

CWE-122

Heap-based Buffer Overflow

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