5.3

CVE-2021-4189: debian debian_linux Unchecked Return Value

Modified
AliasesUBUNTU-CVE-2021-4189DEBIAN-CVE-2021-4189openSUSE-SU-2024:11835-1
Published 24-08-2022Last modified 14-10-2026

Vulnerability summary

CVE-2021-4189 is a medium (CVSS 5.3) Unchecked Return Value vulnerability in debian debian_linux. EPSS estimates a 3.41% chance of exploitation in the next 30 days, higher than 88.8% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 5.3, network access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
5.3/10
010
Medium · v3.1 (CVE.org)
EPSS score
3.41%
0%100%
Low · +0.21 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 27 · Related 18
DLA-2919-1DLA-3432-1DLA-3477-1DLA-3980-1MGASA-2022-0367OPENSUSE-SU-2022:1091-1

Timeline

  1. 24-08-2022
    PublishedVulnerability first disclosed.
  2. 14-10-2026
    Last modifiedVulnerability information updated.

Description

A flaw was found in Python, specifically in the FTP (File Transfer Protocol) client library in PASV (passive) mode. The issue is how the FTP client trusts the host from the PASV response by default. This flaw allows an attacker to set up a malicious FTP server that can trick FTP clients into connecting back to a given IP address and port. This vulnerability could lead to FTP client scanning ports, which otherwise would not have been possible.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

3.41%

Chance of exploitation in the next 30 days

Percentile

89%

Versus all other CVEs

30-day change

Increase +0.21 pp

From 3.20% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu6 products
  • python2.7< 2.7.6-8ubuntu0.6+esm12 | < 2.7.12-1ubuntu0~16.04.18+esm1 | < 2.7.17-1~18.04ubuntu1.7 | < 2.7.18-1~20.04.3+esm1 | < 2.7.18-13ubuntu1.1+esm2
  • python3.4< 3.4.3-1ubuntu1~14.04.7+esm12
  • python3.5< 3.5.2-2ubuntu0~16.04.4~14.04.1+esm1 | < 3.5.2-2ubuntu0~16.04.13+esm2
  • python3.6< 3.6.9-1~18.04ubuntu1.7
  • python3.7< 3.7.5-2ubuntu1~18.04.2+esm3
Debian2 products
Redhat2 products
Netapp1 product
Opensuse1 product
  • python&distro=openSUSE Tumbleweed< 2.7.18-15.1
Python1 product
  • pythonEOL≥ 3.6.0, < 3.6.14 | ≥ 3.7.0, < 3.7.11 | ≥ 3.8.0, < 3.8.9 | ≥ 3.9.0, < 3.9.3 | 3.10.0

6 vendors · 13 products

References

21 links
Show all 21 references