CVE-2026-129122

high

Description

C-Kermit 6.0.192 before 11.1.515 contains a buffer overflow vulnerability in tn_snenv() in ckctel.c that allows malicious Telnet servers to corrupt client memory via crafted NEW-ENVIRON SEND subnegotiation. Malicious or machine-in-the-middle servers can send oversized variable names before authentication, overflowing a 16-byte stack buffer and a miscomputed heap buffer to corrupt stack and heap memory.

References

https://www.vulncheck.com/advisories/c-kermit-6.0.192-before-11.1.515-buffer-overflow-via-telnet-new-environ-negotiation

https://github.com/OpenKermit/ckermit/security/advisories/GHSA-c5px-7h4c-gj8p

https://github.com/OpenKermit/ckermit/releases/tag/v11.1.515

https://github.com/OpenKermit/ckermit/commit/42cf6decb926f56d606a76262791aaf071955d25

https://github.com/OpenKermit/ckermit/commit/39ab009a365b97632e9975e1266fa618c4bdc59f

https://github.com/OpenKermit/ckermit/blob/v11.0.514/ckctel.c#L5622

https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-125557

Details

Source: Mitre, NVD

Published: 2026-11-13

Updated: 2026-11-13

Risk Information

CVSS v2

Base Score: 7.6

Vector: CVSS2#AV:N/AC:H/Au:N/C:C/I:C/A:C

Severity: High

CVSS v3

Base Score: 7.5

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

Severity: High

CVSS v4

Base Score: 7.7

Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Severity: High

EPSS

EPSS: 0.00455