CVE-2026-67191 Details
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.
A heap buffer overflow vulnerability has been identified in Xlight FTP Server versions prior to 3.9.5. This vulnerability allows remote, unauthenticated attackers to write beyond the end of a heap buffer by sending a malformed SSH client identification string. The issue arises from a logic error in the termination condition of the receive loop, which incorrectly uses an OR operator instead of an AND operator. This flaw enables exploitation on any SSH or SFTP connection before authentication.
Users are advised to upgrade to Xlight FTP Server version 3.9.5 or later, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jul 29, 2026CISA-ADP
Assessed Jul 29, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://www.vulncheck.com/advisories/xlight-ftp-server-pre-auth-heap-buffer-overflow-via-ssh-parser | [email protected] | Advisory |
| https://www.xlightftpd.com/whatsnew.htm | [email protected] | Release NotesVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-122 | Heap-based Buffer Overflow | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Xlight FTP Server | < 3.9.5 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 29, 2026 | CVE Modified | CISA-ADP |
| Jul 29, 2026 | New CVE Received | [email protected] |