CVE-2026-44431: urllib3 is an HTTP client library for Python

Routine

MEDIUM 5.3REMOTEUPGRADE

CVE-2026-44431 is a medium-severity flaw (CVSS 5.3) affecting urllib3. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 74%)
CISA exploited list	No
Weakness	CWE-200
Published	2026-05-13
Last modified	2026-06-26

Publisher (CNA): GitHub, Inc. · Vendor: python

Last updated 2026-06-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-13 16:16 UTCPublished CVE record published
2026-06-26 12:16 UTCUpdated Record last modified

python urllib3 UPGRADE

Affected: >= 1.23 and < 2.7.0

Fixed in: 2.7.0

Safe to downgrade to: a release before 1.23

1. Check installed version

apt-cache policy urllib3 || rpm -q urllib3 || urllib3 --version

2. UPGRADE to 2.7.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade urllib3

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade urllib3

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 1.23 (Debian / Ubuntu)

apt-cache madison urllib3 sudo apt install urllib3=<VERSION_BEFORE_1.23> sudo apt-mark hold urllib3

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list urllib3 sudo dnf downgrade urllib3-<VERSION_BEFORE_1.23> sudo dnf versionlock add urllib3

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Advisories and coverage

Official advisories

AlmaLinux Errata: [ALSA-2026:28159] Important: python3.12-urllib3 security update 2026-06-25
AlmaLinux Errata: [ALSA-2026:28158] Important: python-urllib3 security update 2026-06-25
AlmaLinux Errata: [ALSA-2026:28157] Important: python3.14-urllib3 security update 2026-06-25

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-44431?

urllib3: upgrade to 2.7.0. Exact commands for each OS are on this page.

Is CVE-2026-44431 being exploited?

CVE-2026-44431 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-44431 affect?

CVE-2026-44431 affects urllib3. Severity is medium (CVSS 5.3). 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 header

How urgent is CVE-2026-44431?

Priority 30/100. Remotely exploitable, no login, no user action

Software pages

Python vulnerabilities

Related CVEs

CVE-2026-97687 HIGH 8.1 UPGRADE urllib3 is an HTTP client library for Python
CVE-2026-97688 MEDIUM 5.3 UPGRADE urllib3 is an HTTP client library for Python
CVE-2026-97689 HIGH 7.5 UPGRADE urllib3 is an HTTP client library for Python
CVE-2026-44432 HIGH 7.5 UPGRADE urllib3 is an HTTP client library for Python

References

← Back to latest CVEs