# CVE-2026-119600: tcpflow through 1.6.1 Out-of-Bounds Read via TCP Demultiplexer Payload Length

Status: published. Published: 2026-10-30. Updated: 2026-11-04.

tcpflow through 1.6.1 contains an out-of-bounds read vulnerability that allows unauthenticated attackers to read process memory by sending packets with forged IP payload lengths. Attackers can inject crafted IPv4 or IPv6 TCP packets into captured traffic or pcap files to leak adjacent memory into reconstructed flow files or crash tcpflow.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- simsong / tcpflow: ≥ 0; ≤ 1.6.1 (affected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 6.3 (medium); CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 4.8 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L; source: CNA: VulnCheck

- CVSS 4.0: 6.3 (medium); CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/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; source: NVD: disclosure@vulncheck.com

- CVSS 3.1: 4.8 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L; source: NVD: disclosure@vulncheck.com

- CISA KEV: No listing in collected sources

- EPSS: 0.37% as of 2026-11-04; percentile 31.42%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-130

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/simsong/tcpflow/issues/279 (CNA: VulnCheck; issue-tracking)

- https://github.com/simsong/tcpflow/blob/tcpflow-1.6.1/src/tcpdemux.cpp#L781 (CNA: VulnCheck; technical-description)

- https://github.com/simsong/tcpflow/blob/tcpflow-1.6.1/src/tcpdemux.cpp#L747 (CNA: VulnCheck; technical-description)

- https://hackmd.io/@haindpwn/tcpflow-ip-payload-length-oob-read (CNA: VulnCheck; third-party-advisory)

- https://github.com/simsong/tcpflow (CNA: VulnCheck; product)

- https://www.vulncheck.com/advisories/tcpflow-through-1.6.1-out-of-bounds-read-via-tcp-demultiplexer-payload-length (CNA: VulnCheck; third-party-advisory)

- https://github.com/simsong/tcpflow (disclosure@vulncheck.com)

- https://github.com/simsong/tcpflow/blob/tcpflow-1.6.1/src/tcpdemux.cpp#L747 (disclosure@vulncheck.com)

- https://github.com/simsong/tcpflow/blob/tcpflow-1.6.1/src/tcpdemux.cpp#L781 (disclosure@vulncheck.com)

- https://github.com/simsong/tcpflow/issues/279 (disclosure@vulncheck.com)

- https://hackmd.io/@haindpwn/tcpflow-ip-payload-length-oob-read (disclosure@vulncheck.com)

- https://www.vulncheck.com/advisories/tcpflow-through-1.6.1-out-of-bounds-read-via-tcp-demultiplexer-payload-length (disclosure@vulncheck.com)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-119600; retrieved 2026-11-04; source updated 2026-11-04

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-119600; retrieved 2026-11-05; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-119600; retrieved 2026-11-04; source updated Not reported

Revision: b4e32b8baf6cc8d88c9077ddde35cb1735dfc77f98e7ee0893803ef9a5f294d8

Canonical: https://y2.dev/cve/CVE-2026-119600

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