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Public proof of concept

CVE-2026-121944

sngrep through 1.9.0 Infinite Loop DoS via Crafted NFLOG TLV

A public proof of concept exists; no exploitation attested.

  • Published2026-11-04
  • WeaknessCWE-835

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2026-11-0412:31CVE publishedCNA

Versions per branch

Products declared by the CNA1 product

As VulnCheck, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-11-04

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • sngrepUbuntu:26.10all versions · no fixed version listed
  • sngrepUbuntu:26.04:LTSall versions · no fixed version listed
  • sngrepUbuntu:24.04:LTSall versions · no fixed version listed
  • sngrepUbuntu:22.04:LTSall versions · no fixed version listed
  • sngrepUbuntu:20.04:LTSall versions · no fixed version listed
  • sngrepUbuntu:18.04:LTSall versions · no fixed version listed
  • sngrepUbuntu:16.04:LTSall versions · no fixed version listed

Vendor advisories

  • CVE-2026-121944 Red Hat Product Security

    sngrep: sngrep: Denial of Service via crafted packet capture file

Full record on NVD

Fix

No fix published by the sources we read yet. NVD record

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

  • CISA-ADPSSVC decisionpoc2026-11-04
  • CNACVSS 4.06.82026-11-04
  • CNACVSS 3.15.52026-11-04
  • NVDCVSS 3.15.5read 2026-11-05
  • CNAweakness (CWE)CWE-8352026-11-04
  • NVDweakness (CWE)CWE-835read 2026-11-05
  • FIRST EPSSEPSS score0.2 %2026-11-05
  • OSVaffected packages—
  • GitHub Advisoriesadvisory—

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CVSS 4.0 vector
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/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
Published
2026-11-04
Last Modified
2026-11-04
NVD status
Deferred
GitHub Advisory
GHSA-5wr4-785p-23qx

Frequently asked questions

What is CVE-2026-121944?

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.

Is CVE-2026-121944 actively exploited?

A proof-of-concept exploit exists for CVE-2026-121944, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-121944?

CVE-2026-121944 has a CVSS v3 base score of 5.5 (MEDIUM severity), with vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.

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Sources for this record