How severe is CVE-2021-40239?

CVE-2021-40239 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-40239 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-40239?

CVE-2021-40239 affects Miniftpd Project Miniftpd. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-40239?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-40239 published?

CVE-2021-40239 was published on 2021-10-11 and last updated on 2026-06-17.

CVE-2021-40239

CVE-2021-40239 is a critical-severity vulnerability in Miniftpd Project Miniftpd with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-120.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 1% (68th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
Affected product: Miniftpd Project Miniftpd
Published: 2021-10-11
Last modified: 2026-06-17

Description

A Buffer Overflow vulnerability exists in the latest version of Miniftpd in the do_retr function in ftpproto.c

Frequently asked questions

What is CVE-2021-40239?: A Buffer Overflow vulnerability exists in the latest version of Miniftpd in the do_retr function in ftpproto.c
How severe is CVE-2021-40239?: CVE-2021-40239 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-40239 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-40239?: CVE-2021-40239 affects Miniftpd Project Miniftpd. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-40239?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-40239 published?: CVE-2021-40239 was published on 2021-10-11 and last updated on 2026-06-17.

References

https://github.com/Gabe-commiter/Miniftpd/issues/2

Affected products (1)

cpe:2.3:a:miniftpd_project:miniftpd:1.0:*:*:*:*:*:*:*

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