CVE-2026-121969

netrek-client-cow through 3.3.3 Stack Buffer Overflow via handleSMessage

7.1 High

netrek-client-cow through 3.3.3 contains a stack-based buffer overflow vulnerability in handleSMessage() in short.c that allows malicious servers to overflow a 100-byte stack buffer by sending oversized SP_S_MESSAGE packets. A malicious Netrek server or man-in-the-middle on the plaintext TCP connection can send overlong or unterminated message bodies to write server-controlled bytes onto the stack and crash the client.

Attack profile

How easy it is to exploit

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

What an attacker can affect

Confidentiality: None
Integrity: None
Availability: High

Exploit likelihood

0.34%Unchanged since Nov 5, 2026

What each source reports

CVE List Score used 7.1

netrek-client-cow through 3.3.3 Stack Buffer Overflow via handleSMessage

Record: CVE-2026-121969
CVSS 4.0: 7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness: CWE-121
Updated: 2026-11-05

EUVDEUVD-2026-117080 7.1

Record: EUVD-2026-117080
CVSS 4.0: 7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Updated: 2026-11-05

GitHub AdvisoriesGHSA-2v39-q9qf-3m9g 7.1

netrek-client-cow through 3.3.3 contains a stack-based buffer overflow vulnerability in...

Record: GHSA-2v39-q9qf-3m9g
CVSS 4.0: 7.1 HighCVSS:4.0/AV:N/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
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness: CWE-121
Updated: 2026-11-04

NVD 7.1

Record: CVE-2026-121969
CVSS 4.0: 7.1 HighCVSS:4.0/AV:N/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
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness: CWE-121
Updated: 2026-11-05

OSV 7.1

netrek-client-cow through 3.3.3 Stack Buffer Overflow via handleSMessage

Record: CVE-2026-121969
CVSS 4.0: 7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness: CWE-121
Updated: 2026-11-07

OSVUBUNTU-CVE-2026-121969 7.1

Record: UBUNTU-CVE-2026-121969
CVSS 4.0: 7.1 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated: 2026-11-06

Affected products

quozl netrek-client-cow

Affected packages

Affected packages
Package	Affected	Fixed
`netrek-client-cow` Ubuntu:16.04:LTS	All versions, plus listed versions 3.3.0-3.1	None known
`netrek-client-cow` Ubuntu:18.04:LTS	All versions, plus listed versions 3.3.1-1	None known
`netrek-client-cow` Ubuntu:20.04:LTS	All versions, plus listed versions 3.3.1-4build1	None known
`netrek-client-cow` Ubuntu:22.04:LTS	All versions, plus listed versions 3.3.2-1	None known
`netrek-client-cow` Ubuntu:24.04:LTS	All versions, plus listed versions 3.3.2-13.3.2-1build13.3.2-1build2	None known
`netrek-client-cow` Ubuntu:26.10	All versions, plus listed versions 3.3.2-1build33.3.3-1	None known
`netrek-client-cow` Ubuntu:26.04:LTS	All versions, plus listed versions 3.3.2-1build23.3.2-1build3	None known

History

History
Recorded	Changed	Sources
Nov 6, 2026	affected, aliases, references	CVE List, EUVD, NVD, OSV
Nov 5, 2026	references	OSV
Nov 5, 2026	published	EUVD
Nov 4, 2026	published	EUVD, NVD
Nov 4, 2026	aliases, published	EUVD
Nov 4, 2026	first indexed	CVE List, GitHub Advisories

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

In short

CVE-2026-121969 is a high vulnerability (CVSS 7.1) in Quozl Netrek-client-cow, published November 4, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.34%, the 28th percentile. No source names a fixed version.

References

Show 4 moreShow less