CVE-2021-29921

highpriority · track · 41EPSS 0.069 · 94 %ileDEEURUUS
grimoire priorityP2 · Scheduled
Exploitable?
—
no known exploitation
Likely / severe?
6.88% (94th) EPSS
CVSS 7.5 · high
Is it mine?
55 products
Check your exposure
Who says so?
5 sources
cnnvd · enisa_euvd · fstec_bdu · osv

EPSS · scored 2026-10-26

In Python before 3,9,5, the ipaddress library mishandles leading zero characters in the octets of an IP address string. This (in some situations) allows attackers to bypass access control that is based on IP addresses.

01

cvss

Technical severity, 0–10. One row per scoring source.

9.8
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · high–critical · 7.5–9.8

v2.07.5highAV:N/AC:L/Au:N/C:P/I:P/A:Pprimary · NVD / NIST USexploitability 10 · impact 6.4
v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 5.9
v3.19.8criticalAV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsecondary · FSTEC (BDU) RU
v3.19criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:Usecondary · CVSS-BT (t0sche)
02

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: yes · Technical Impact: totalcoordinatorcisa_ssvcUS
03

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-20US
04

affected products (55)

Products and version ranges known to be affected.

showing 20 of 55
05

advisories (6)

Vendor and ecosystem advisories describing this.

  • WID-SEC-W-2022-0464Oracle Java SE: Mehrere SchwachstellenDeutsch2021-07-20csaf · cert_bundDE

    Ein entfernter, anonymer oder lokaler Angreifer kann mehrere Schwachstellen in Oracle Java SE ausnutzen, um die Vertraulichkeit, Integrität und Verfügbarkeit zu gefährden.

  • WID-SEC-W-2023-2460Python: Schwachstelle ermöglicht ManipulationDeutsch2021-05-03csaf · cert_bundDE

    Ein entfernter, anonymer Angreifer kann eine Schwachstelle in Python ausnutzen, um Dateien zu manipulieren.

  • BIT-libpython-2021-299212025-08-11vendor · osvUS

    In Python before 3,9,5, the ipaddress library mishandles leading zero characters in the octets of an IP address string. This (in some situations) allows attackers to bypass access control that is based on IP addresses.

  • BIT-python-2021-299212024-03-06vendor · osvUS

    In Python before 3,9,5, the ipaddress library mishandles leading zero characters in the octets of an IP address string. This (in some situations) allows attackers to bypass access control that is based on IP addresses.

  • BIT-python-min-2021-299212025-01-16vendor · osvUS

    In Python before 3,9,5, the ipaddress library mishandles leading zero characters in the octets of an IP address string. This (in some situations) allows attackers to bypass access control that is based on IP addresses.

  • PSF-2021-2ipaddress leading zeros in IPv4 address2021-05-06vendor · osvUS

    In Python before 3,9,5, the ipaddress library mishandles leading zero characters in the octets of an IP address string. This (in some situations) allows attackers to bypass access control that is based on IP addresses.

06

also known as (8)

Other names and identifiers for this entity.

07

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bduosvcert_bundNVDCVE.orgMITRE
published 2021-05-06modified 2026-10-09
08

references (68)

External citations — patches, advisories, analysis.

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