7.5

CVE-2021-33503: fedoraproject fedora Uncontrolled Resource Consumption

Modified
AliasesSUSE-RU-2021:2194-1SUSE-SU-2021:2012-1SUSE-SU-2021:2195-1
Published 29-06-2021Last modified 03-08-2024

Vulnerability summary

CVE-2021-33503 is a high (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in fedoraproject fedora. EPSS estimates a 3.27% chance of exploitation in the next 30 days, higher than 88.4% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 7.5 (NVD); no exploitation reported by the 5 checked sources; EPSS 3% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
7.5/10
010
High · v3.1 (NVD)
EPSS score
3.27%
0%100%
Low · 0.00 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 10 · Related 4
MGASA-2021-0371MGASA-2021-0377OPENSUSE-SU-2024:11277-1OPENSUSE-SU-2024:14055-1OPENSUSE-SU-2026:12044-1OPENSUSE-SU-2026:12045-1

Timeline

  1. 29-06-2021
    PublishedVulnerability first disclosed.
  2. 03-08-2024
    Last modifiedVulnerability information updated.

Description

An issue was discovered in urllib3 before 1.26.5. When provided with a URL containing many @ characters in the authority component, the authority regular expression exhibits catastrophic backtracking, causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.

CVSS metrics

8 scores · 6 sources · 3 versions

EPSS trend

Probability

3.27%

Chance of exploitation in the next 30 days

Percentile

88%

Versus all other CVEs

30-day change

No change 0.00 pp

From 3.27% 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.

Suse175 products
  • aws-cli&distro=HPE Helion OpenStack 8< 1.19.9-22.24.2
  • aws-cli&distro=SUSE Linux Enterprise Module for Public Cloud 12< 1.19.9-22.24.2
  • aws-cli&distro=SUSE OpenStack Cloud 8< 1.19.9-22.24.2
  • aws-cli&distro=SUSE OpenStack Cloud Crowbar 8< 1.19.9-22.24.2
  • azure-cli-command-modules-nspkg&distro=SUSE Linux Enterprise Module for Public Cloud 12< 2.0.3-2.10.2
Redhat13 products
  • automation-hub< 0:4.2.6-1.el7pc | < 0:4.2.6-1.el8pc
  • python-galaxy-ng< 0:4.2.6-1.el7pc | < 0:4.2.6-1.el8pc
  • python-urllib3< 0:1.26.5-1.el7pc | < 0:1.26.5-1.el8pc
  • python3-chardet< 0:3.0.4-3.el7pc
  • python3-click< 0:7.1.2-3.el7pc | < 0:7.1.2-3.el8pc
Oracle3 products
Chainguard2 products
  • py3.13-scanner-test-scanner-test-python-vulnerability-fixedAll versions (No fix recorded)
  • py3.13-scanner-test-scanner-test-python-vulnerability-unfixedAll versions (No fix recorded)
Ubuntu2 products
  • python-pip< 20.0.2-5ubuntu1.7
  • python-urllib3< 1.25.8-2ubuntu0.2
Debian1 product
  • python-urllib3< 1.26.5-1~exp1
Fedoraproject1 product
Opensuse1 product
  • python-urllib3&distro=openSUSE Leap 15.3< 1.25.10-4.3.1
PyPI1 product
  • urllib3< 2d4a3fee6de2fa45eb82169361918f759269b4ec | ≥ 5b047b645f5f93900d5e2fc31230848c25eb1f5f, < 2d4a3fee6de2fa45eb82169361918f759269b4ec | ≥ 1.25.4, < 1.26.5
Python1 product

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References

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