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CVE-2026-44431 — urllib3

CVE-2026-44431 is a Information Exposure vulnerability in urllib3. A fix is available for urllib3 — see the affected versions and patch details below.

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

Also known asGHSA-qccp-gfcp-xxvcPYSEC-2026-141
Published
May 13, 2026
Updated
Aug 12, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Sep 23, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-44431.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs27th percentile — riskier than 27% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

1 pkg affected
🐍urllib3

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Impact

When following cross-origin redirects for requests made using urllib3’s high-level APIs, such as urllib3.request(), PoolManager.request(), and ProxyManager.request(), sensitive headers — Authorization, Cookie, and Proxy-Authorization (defined in Retry.DEFAULT_REMOVE_HEADERS_ON_REDIRECT) — are stripped by default, as expected.

However, cross-origin redirects followed from the low-level API via ProxyManager.connection_from_url().urlopen(..., assert_same_host=False) still forward these sensitive headers.

Affected usage

Applications and libraries using urllib3 versions earlier than 2.7.0 may be affected if they allow cross-origin redirects while making requests through HTTPConnection.urlopen() instances created via ProxyManager.connection_from_url().

Remediation

Upgrade to urllib3 version 2.7.0 or later, in which sensitive headers are stripped from redirects followed by HTTPConnection.

If upgrading is not immediately possible, avoid using this low-level redirect flow for cross-origin redirects. If appropriate for your use case, switch to ProxyManager.request().

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIurllib3≥ 1.23&&< 2.7.02.7.0pip install --upgrade 'urllib3==2.7.0'

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for urllib3, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update urllib3 to 2.7.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-44431 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-44431 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2026-44431. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate
ProductFixed inAdvisory
Red Hat Ansible Automation Platform 2.6 for RHEL 9python3.12-urllib3-0:2.7.0-1.el9apRHSA-2026:34160
Red Hat Enterprise Linux 10python3.14-urllib3-0:2.6.3-2.el10_2RHSA-2026:27929
Red Hat Enterprise Linux 10python-urllib3-0:1.26.19-4.el10_2RHSA-2026:28000
Red Hat Enterprise Linux 8python3.12-urllib3-0:1.26.19-3.el8_10RHSA-2026:32992
Red Hat Enterprise Linux 8fence-agents-0:4.2.1-129.el8_10.28RHSA-2026:49927
Red Hat Enterprise Linux 8resource-agents-0:4.9.0-54.el8_10.36RHSA-2026:47126
Red Hat Enterprise Linux 8python-urllib3-0:1.24.2-10.el8_10RHSA-2026:36732
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Supportfence-agents-0:4.2.1-65.el8_4.31RHSA-2026:51152
UbuntuMEDIUM
USN-8379-1Ubuntu

Frequently Asked Questions

### Impact When following cross-origin redirects for requests made using urllib3’s high-level APIs, such as `urllib3.request()`, `PoolManager.request()`, and `ProxyManager.request()`, sensitive headers — `Authorization`, `Cookie`, and `Proxy-Authorization` (defined in `Retry.DEFAULT_REMOVE_HEADERS_ON_REDIRECT`) — are stripped by default, as expected. However, cross-origin redirects followed from the low-level API via `ProxyManager.connection_from_url().urlopen(..., assert_same_host=False)` still forward these sensitive headers. ### Affected usage Applications and libraries using urllib3 ve
O3 Security · Impact-Aware SCA

Is CVE-2026-44431 in your dependencies?

O3 Security finds CVE-2026-44431 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

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CVE-2026-44431: urllib3 | O3 Security