Is CVE-2026-67191 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-67191 being exploited in the wild.

How severe is CVE-2026-67191?

Critical severity, with a CVSS score of 9.8, published 29 July 2026.

Which products and versions are affected?

Xlight Xlight FTP Server before 3.9.5.

Is there a fix for CVE-2026-67191?

A patch was published on 2026-07-01: Version 3.9.5 released to address security vulnerabilities. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-67191 attacked?

It is attacked over the network, in a hosted service.

Am I affected by CVE-2026-67191?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-67191: Xlight FTP Server heap buffer overflow in SSH parser

CVE-2026-67191 · Severity: critical · CVSS 9.8 · Published 2026-07-29

Xlight FTP Server, a high-performance file transfer server, is vulnerable to a critical security flaw in its SSH and SFTP handling. An unauthenticated remote attacker can exploit this vulnerability to gain full control over the server or cause it to crash by sending a specially crafted identification string. This could lead to the theft of sensitive customer data, complete service disruption, and a significant impact on business operations.

Quick answers

Is CVE-2026-67191 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-67191 being exploited in the wild.
How severe is CVE-2026-67191?: Critical severity, with a CVSS score of 9.8, published 29 July 2026.
Which products and versions are affected?: Xlight Xlight FTP Server before 3.9.5.
Is there a fix for CVE-2026-67191?: A patch was published on 2026-07-01: Version 3.9.5 released to address security vulnerabilities. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-67191 attacked?: It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-67191?: Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A heap-based buffer overflow vulnerability exists in Xlight FTP Server versions prior to 3.9.5 due to a logic error in the SSH client identification string parser. The root cause is an incorrect use of an OR operator instead of an AND operator in the receive loop's termination condition, which allows an attacker to write data past the end of a heap buffer. This vulnerability is reachable over the network without authentication via any SSH or SFTP connection. Successful exploitation can lead to arbitrary code execution or a server crash. The issue was addressed in version 3.9.5.

Affected products

Xlight Xlight FTP Server before 3.9.5

Timeline

2026-07-01: patched: Version 3.9.5 released to address security vulnerabilities.
2026-07-29: disclosed: Vulnerability details published by VulnCheck and NVD.

References

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