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[USN-8344-2] pip regression

Posted on 30 May 2026
Ubuntu Security

==========================================================================Ubuntu Security Notice USN-8344-2
May 29, 2026

python-pip regression
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 26.04 LTS
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS

Summary:

USN-8344-1 introduced a regression in pip.

Software Description:
- python-pip: Python package installer

Details:

USN-8344-1 fixed vulnerabilities in pip. On Ubuntu 22.04 LTS, Ubuntu 24.04 LTS,
and Ubuntu 26.04 LTS the patches for CVE-2025-66471 caused a regression when
using pip. The patches for CVE-2025-66471 have been temporarily reverted
pending investigation.

We apologize for the inconvenience.

Original advisory details:

It was discovered that pip incorrectly handled TLS certificate
verification in session connections. If a session was first used with
certificate verification disabled, subsequent requests to the same host
would also skip verification regardless of the session's current settings.
A remote attacker could possibly use this issue to perform a machine-in-the-middle
attack and expose sensitive information. (CVE-2024-35195)

It was discovered that pip's bundled urllib3 library did not limit the
number of decompression steps when processing HTTP responses. A remote
attacker could possibly use this issue to cause pip to consume excessive resources,
leading to a denial of service. (CVE-2025-66418)

It was discovered that pip's bundled urllib3 library improperly
handled streaming decompression of highly compressed data. A remote
attacker could possibly use this issue to cause pip to consume excessive resources,
leading to a denial of service. (CVE-2025-66471)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 26.04 LTS
python3-pip 25.1.1+dfsg-1ubuntu2+esm2
Available with Ubuntu Pro
python3-pip-whl 25.1.1+dfsg-1ubuntu2+esm2
Available with Ubuntu Pro

Ubuntu 24.04 LTS
python3-pip 24.0+dfsg-1ubuntu1.3+esm2
Available with Ubuntu Pro
python3-pip-whl 24.0+dfsg-1ubuntu1.3+esm2
Available with Ubuntu Pro

Ubuntu 22.04 LTS
python3-pip 22.0.2+dfsg-1ubuntu0.7+esm2
Available with Ubuntu Pro
python3-pip-whl 22.0.2+dfsg-1ubuntu0.7+esm2
Available with Ubuntu Pro

In general, a standard system update will make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-8344-2
https://ubuntu.com/security/notices/USN-8344-1
https://launchpad.net/bugs/2154576

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