CVE-2026-112021

High

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.

SeverityHigh

CVSS7.5

Exploit probability—

ProductGrunfink Snac2

PublishedOct 18, 2026

First seenOct 18, 2026

Weakness typeCWE-122CWE-122

How to fix

Update

grunfink snac22.93 or later

Patches

codeberg.org/grunfink/snac2/commit/ec2c5c2046e0381bc942ec5d0d05ec861fe377e7

Vendor advisories

codeberg.org/grunfink/snac2/releases/tag/2.93

Affected products

Product	Affected versions	Fixed in
grunfink snac2	v < 2.93	2.93

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