CVE-2026-44431

urllib3: Sensitive headers forwarded across origins in proxied low-level redirects

Published May 13, 2026 CVSS 4.0 · 8.2 High EPSS < 1% KEV · Not listed
Description
urllib3 is an HTTP client library for Python. From 1.23 to before 2.7.0, cross-origin redirects followed from the low-level API via ProxyManager.connection_from_url().urlopen(..., assert_same_host=False) still forward these sensitive headers. This vulnerability is fixed in 2.7.0.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4651-1 python-urllib3 security update
Debian DSA Debian DSA DSA-6363-1 python-urllib3 security update
Github GHSA Github GHSA GHSA-qccp-gfcp-xxvc urllib3: Sensitive headers forwarded across origins in proxied low-level redirects
Ubuntu USN Ubuntu USN USN-8379-1 urllib3 vulnerabilities
Ubuntu USN Ubuntu USN USN-8811-1 urllib3 vulnerability
History
Type Values Removed Values Added
First Time appeared Python
Python urllib3
Weaknesses NVD-CWE-noinfo
CPEs cpe:2.3:a:python:urllib3:*:*:*:*:*:*:*:*
Vendors & Products Python
Python urllib3
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'}

Type Values Removed Values Added
First Time appeared Urllib3
Urllib3 urllib3
Vendors & Products Urllib3
Urllib3 urllib3
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description urllib3 is an HTTP client library for Python. From 1.23 to before 2.7.0, cross-origin redirects followed from the low-level API via ProxyManager.connection_from_url().urlopen(..., assert_same_host=False) still forward these sensitive headers. This vulnerability is fixed in 2.7.0.
Title urllib3: Sensitive headers forwarded across origins in proxied low-level redirects
Weaknesses CWE-200
References
Metrics cvssV4_0

{'score': 8.2, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N'}

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jun 26, 2026, 11:01 AM
Reserved
May 6, 2026, 2:40 PM
Status
Modified
Published
May 13, 2026, 4:16 PM
Modified
Nov 11, 2026, 8:10 PM
Severity
Moderate
Public date
May 13, 2026, 3:20 PM