CVE-2017-15271: A use-after-free issue could be triggered remotely in the SFTP component of PSFTPd 10.0.4 Build 729

This week

MEDIUM 5.9REMOTEDOWNGRADE

CVE-2017-15271 is a medium-severity flaw (CVSS 5.9) affecting psftpd. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 th

Why this priority

EPSS top 5%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	8.7% (top 5%)
CISA exploited list	No
Weakness	CWE-416
Published	2017-11-15
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: psftp

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2017-11-15 16:29 UTCPublished CVE record published
2026-06-17 01:07 UTCUpdated Record last modified

psftp psftpd DOWNGRADE

Affected: 10.0.4

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.0.4

1. Check installed version

apt-cache policy psftpd || rpm -q psftpd || psftpd --version

2. No fixed release: DOWNGRADE to a release before 10.0.4 (Debian / Ubuntu)

apt-cache madison psftpd sudo apt install psftpd=<VERSION_BEFORE_10.0.4> sudo apt-mark hold psftpd

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list psftpd sudo dnf downgrade psftpd-<VERSION_BEFORE_10.0.4> sudo dnf versionlock add psftpd

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: PSFTPd Windows FTP Server 10.0.4 Build 729 - Log Injection / Use-After-Free

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2017-15271?

psftpd: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2017-15271 being exploited?

CVE-2017-15271 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2017-15271 affect?

CVE-2017-15271 affects psftpd. Severity is medium (CVSS 5.9). 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

How urgent is CVE-2017-15271?

Priority 54/100. EPSS top 5%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2017-15272 MEDIUM 5.3 DOWNGRADE The PSFTPd 10.0.4 Build 729 server stores its configuration inside PSFTPd.dat
CVE-2017-15270 MEDIUM 5.3 DOWNGRADE The PSFTPd 10.0.4 Build 729 server does not properly escape data before writing it into a Comma Separated Valu
CVE-2017-15269 MEDIUM 4.3 DOWNGRADE The PSFTPd 10.0.4 Build 729 server does not prevent FTP bounce scans by default

References

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