CVE-2017-15271

Severity: medium (CVSS 5.9 v3.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 8.7% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2017-11-15 · updated 2026-06-17
Weakness: CWE-416

Description

A use-after-free issue could be triggered remotely in the SFTP component of PSFTPd 10.0.4 Build 729. This issue could be triggered prior to authentication. The PSFTPd server did not automatically restart, which enabled attackers to perform a very effective DoS attack against this service. By sending a crafted SSH identification / version string to the server, a NULL pointer dereference could be caused, apparently because of a race condition in the window message handling, performing the cleanup for invalid connections. This incorrect cleanup code has a use-after-free.

Affected products

Psftpd: 10.0.4

References

http://packetstormsecurity.com/files/144972/PSFTPd-Windows-FTP-Server-10.0.4-Build-729-Use-After-Free-Log-Injection.html
http://www.securityfocus.com/archive/1/541518/100/0/threaded
https://www.exploit-db.com/exploits/43144/
https://www.x41-dsec.de/lab/advisories/x41-2017-006-psftpd/
http://packetstormsecurity.com/files/144972/PSFTPd-Windows-FTP-Server-10.0.4-Build-729-Use-After-Free-Log-Injection.html
http://www.securityfocus.com/archive/1/541518/100/0/threaded
https://www.exploit-db.com/exploits/43144/
https://www.x41-dsec.de/lab/advisories/x41-2017-006-psftpd/

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