CVE-2021-39602: A Buffer Overflow vulnerabilty exists in Miniftpd 1.0 in the do_mkd function in the ftpproto.c file, which cou

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MEDIUM 6.5DOWNGRADE

CVE-2021-39602 is a medium-severity flaw (CVSS 6.5) affecting miniftpd. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A Buffer Overflow vulnerabilty exists in Miniftpd 1.0 in the do_mkd function in the ftpproto.c file, which could let a remote malicious user cause a Denial of Service.

Why this priority

Public exploit reference

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

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.8% (top 42%)
CISA exploited list	No
Weakness	CWE-120
Published	2021-08-23
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: miniftpd project

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

Am I affected?

Timeline

2021-08-23 23:15 UTCPublished CVE record published
2026-06-17 04:03 UTCUpdated Record last modified

miniftpd project miniftpd DOWNGRADE

Affected: 1.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.0 (Debian / Ubuntu)

apt-cache madison miniftpd sudo apt install miniftpd=<VERSION_BEFORE_1.0> sudo apt-mark hold miniftpd

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

dnf --showduplicates list miniftpd sudo dnf downgrade miniftpd-<VERSION_BEFORE_1.0> sudo dnf versionlock add miniftpd

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.

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-2021-39602?

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

Is CVE-2021-39602 being exploited?

CVE-2021-39602 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-2021-39602 affect?

CVE-2021-39602 affects miniftpd. Severity is medium (CVSS 6.5). A Buffer Overflow vulnerabilty exists in Miniftpd 1.0 in the do_mkd function in the ftpproto.c file, which could let a remote malicious user cause a Denial of Service.

How urgent is CVE-2021-39602?

Priority 42/100. Public exploit reference

Related CVEs

CVE-2021-42624 HIGH 7.8 MITIGATE A local buffer overflow vulnerability exists in the latest version of Miniftpd in ftpproto.c through the tmp v
CVE-2021-40239 CRITICAL 9.8 DOWNGRADE A Buffer Overflow vulnerability exists in the latest version of Miniftpd in the do_retr function in ftpproto.c

References

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