What’s Vulnerable › Vulnerabilities

CVE-2026-67192: Xlight FTP Server < 3.9.5 Pre-Auth Stack Buffer Overflow via SSH GCM Cipher

• Severity: high (CVSS 8.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.0% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-29 · updated 2026-10-23
• Weakness: CWE-121

Description

Xlight FTP Server before 3.9.5 contains a pre-authentication stack buffer overflow vulnerability that allows unauthenticated attackers to corrupt stack memory by sending malformed SSH packets when a GCM cipher is negotiated. Attackers can craft packets with an unvalidated length field passed directly to the GCM decrypt function, overwriting the stack cookie and return address to potentially achieve remote code execution before any authentication occurs.

Affected products

• Xlight FTP Server: before 3.9.5 — fixed in 3.9.5

How to fix

Upgrade to a fixed version: Xlight FTP Server 3.9.5. Check the vendor advisory for mitigations.

References

• https://www.vulncheck.com/advisories/xlight-ftp-server-pre-auth-stack-buffer-overflow-via-ssh-gcm-cipher
• https://www.xlightftpd.com/whatsnew.htm

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