CVE-2026-67191
Xlight FTP Server < 3.9.5 Pre-Auth Heap Buffer Overflow via SSH Parser
CVSS Score
9.8
EPSS Score
0.0%
EPSS Percentile
0th
Xlight FTP Server before 3.9.5 contains a pre-authentication heap buffer overflow vulnerability that allows remote unauthenticated attackers to write past the end of a heap buffer by sending a malformed SSH client identification string. A logic error in the recv loop's termination condition uses an incorrect OR operator where an AND operator is required, enabling exploitation on any SSH or SFTP connection before authentication occurs.
| CWE | CWE-122 |
| Vendor | xlight |
| Product | xlight ftp server |
| Published | Jul 29, 2026 |
| Last Updated | Jul 29, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Affected Versions
Xlight / Xlight FTP Server
0 < 3.9.5
References
Credits
McCaulay Hudson (@_McCaulay) of watchTowr