Buffer overflow in Quozl Netrek-Client-Cow

CVE-2026-121969

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.

Vulnerability class: Buffer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.003 (28.1th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 28th percentile — 28.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

The 30-day trend appears once there are two daily scores.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-121969?
CVE-2026-121969 is a medium-severity vulnerability in Quozl Netrek-Client-Cow, classified under Stack-based Buffer Overflow. CVSS score: 6.5/10. Published 2026-11-04.
How severe is CVE-2026-121969?
Medium severity. CVSS v3 base score is 6.5 out of 10.