CVE-2026-67191

Xlight FTP Server < 3.9.5 Pre-Auth Heap Buffer Overflow via SSH Parser

Published Jul 29, 2026 CVSS 4.0 · 9.3 Critical EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
CPEs cpe:2.3:a:xlightftpd:xlight_ftp_server:*:*:*:*:*:*:*:*
Type Values Removed Values Added
First Time appeared Xlightftpd
Xlightftpd xlight Ftp Server
Vendors & Products Xlightftpd
Xlightftpd xlight Ftp Server
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Title Xlight FTP Server < 3.9.5 Pre-Auth Heap Buffer Overflow via SSH Parser
Weaknesses CWE-122
References
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

cvssV4_0

{'score': 9.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Aug 14, 2026, 4:50 PM
Reserved
Jul 28, 2026, 4:06 PM
Status
Deferred
Published
Jul 29, 2026, 4:17 PM
Modified
Oct 23, 2026, 11:10 PM