CVE-2026-129122
C-Kermit 6.0.192 before 11.1.515 Buffer Overflow via Telnet NEW-ENVIRON Negotiation
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-787 |
| Vendor | openkermit |
| Product | c-kermit |
| Published | Nov 13, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Affected Versions
OpenKermit / C-Kermit
6.0.192 < 11.1.515
References
github.com: https://github.com/OpenKermit/ckermit/security/advisories/GHSA-c5px-7h4c-gj8p github.com: https://github.com/OpenKermit/ckermit/commit/39ab009a365b97632e9975e1266fa618c4bdc59f github.com: https://github.com/OpenKermit/ckermit/commit/42cf6decb926f56d606a76262791aaf071955d25 github.com: https://github.com/OpenKermit/ckermit/releases/tag/v11.1.515 github.com: https://github.com/OpenKermit/ckermit/blob/v11.0.514/ckctel.c#L5622 vulncheck.com: https://www.vulncheck.com/advisories/c-kermit-6.0.192-before-11.1.515-buffer-overflow-via-telnet-new-environ-negotiation
Credits
John Goerzen John Goerzen