Vulnerability · Published Nov 4, 2026 · Assigned by VulnCheck

CVE-2026-121944sngrep through 1.9.0 Infinite Loop DoS via Crafted NFLOG TLV

Medium 5.5

In plain English

A medium-severity infinite loop in sngrep from irontec. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 15% of all known vulnerabilities).

Severity (CVSS 3.1)5.5Medium

Exploit odds (30 days)0.2%top 85.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

sngrep through 1.9.0 contains an infinite loop vulnerability in capture_packet_reasm_ip() in src/capture.c that allows attackers to cause denial of service via crafted NFLOG TLVs. Attackers can supply a pcap file with link type NFLOG containing a non-payload TLV with length under 4, making the capture thread spin at full CPU and stop processing packets.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	sngrep	no fix listed	DEBIAN-CVE-2026-121944
Debian:13	sngrep	no fix listed	DEBIAN-CVE-2026-121944
Debian:14	sngrep	no fix listed	DEBIAN-CVE-2026-121944
Ubuntu:22.04:LTS	sngrep	no fix listed	UBUNTU-CVE-2026-121944
Ubuntu:24.04:LTS	sngrep	no fix listed	UBUNTU-CVE-2026-121944
Ubuntu:26.04:LTS	sngrep	no fix listed	UBUNTU-CVE-2026-121944
Ubuntu:26.10	sngrep	no fix listed	UBUNTU-CVE-2026-121944

Affected products (as reported)

Vendor	Product	Versions
irontec	sngrep	0 – through 1.9.0

Weakness: CWE-835 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

References

https://github.com/irontec/sngrep/issues/589 issue-tracking
https://hackmd.io/@haindpwn/sngrep-sip-payload-missing-nul-oob-read third-party-advisory
https://github.com/irontec/sngrep/blob/v1.9.0/src/capture.c#L581-L598 technical-description
VulnCheck Advisory: sngrep through 1.9.0 Infinite Loop DoS via Crafted NFLOG TLV third-party-advisory
https://hackmd.io/@haindpwn/cve-2026-121943-121944-sngrep-sip-payload-missing-nul-oob-read exploit