CVE-2026-112021

snac2 before 2.93 contains a heap-based buffer overflow vulnerability in _xs_json_load_lexer()...

8.7 HighFix available

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.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: None
Integrity: None
Availability: High

Exploit likelihood

0.67%Unchanged since Oct 19, 2026

What each source reports

GitHub Advisories Score usedGHSA-6hv3-2r7g-774j 8.7

snac2 before 2.93 contains a heap-based buffer overflow vulnerability in _xs_json_load_lexer()...

Record: GHSA-6hv3-2r7g-774j
CVSS 4.0: 8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-122
Updated: 2026-11-02

EUVDEUVD-2026-103474 8.7

Record: EUVD-2026-103474
CVSS 4.0: 8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Updated: 2026-11-02

OSVDEBIAN-CVE-2026-112021 8.7

Record: DEBIAN-CVE-2026-112021
CVSS 4.0: 8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated: 2026-11-02

OSVUBUNTU-CVE-2026-112021 8.7

Record: UBUNTU-CVE-2026-112021
CVSS 4.0: 8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

Affected products

grunfink snac2

Affected packages

Affected packages
Package	Affected	Fixed
`snac2` Debian:13	All versions, plus listed versions 2.75-22.81-12.81-1~bpo13+12.81-1~bpo13+22.82-1 Show 31 moreShow less 2.82-1~bpo13+12.83-12.83-1~bpo13+12.84-12.84-1~bpo13+12.84-22.84-2~bpo13+12.84-32.84-3~bpo13+12.85-12.85-1~bpo13+12.87-12.87-1~bpo13+12.88-12.88-1~bpo13+12.89-12.89-1~bpo13+12.90-12.90-1~bpo13+12.91-12.91-1~bpo13+12.92-12.92-1~bpo13+12.93-12.93-1~bpo13+12.94-12.94-1~bpo13+12.95-12.95-1~bpo13+12.96-12.96-1~bpo13+1	None known
`snac2` Debian:14	before 2.93-1, plus listed versions 2.75-22.81-12.81-1~bpo13+12.81-1~bpo13+22.82-1 Show 24 moreShow less 2.82-1~bpo13+12.83-12.83-1~bpo13+12.84-12.84-1~bpo13+12.84-22.84-2~bpo13+12.84-32.84-3~bpo13+12.85-12.85-1~bpo13+12.87-12.87-1~bpo13+12.88-12.88-1~bpo13+12.89-12.89-1~bpo13+12.90-12.90-1~bpo13+12.91-12.91-1~bpo13+12.92-12.92-1~bpo13+12.93-1~bpo13+1	2.93-1
`snac2` Ubuntu:24.04:LTS	All versions, plus listed versions 2.25-32.41-12.42-12.42-22.45-12.45-1build22.45-1build3	None known
`snac2` Ubuntu:26.04:LTS	All versions, plus listed versions 2.75-22.84-12.84-22.84-32.85-12.87-12.88-12.89-1	None known

History

History
Recorded	Changed	Sources
Nov 2, 2026	first indexed	EUVD, GitHub Advisories, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-112021 is a high vulnerability (CVSS 8.7) in Grunfink Snac2, published October 18, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.67%, the 52nd percentile. Fixed in snac2 2.93-1.

References

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