CVE-2026-97688: urllib3 is an HTTP client library for Python

Routine

MEDIUM 5.3REMOTEUPGRADE

CVE-2026-97688 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 2.6.2 until 2.8.0, HTTPResponse.stream and HTTPResponse.read_chunked can enter an infinite loop because the Deflate decoder retains trailing bytes as unconsumed input after reaching end-of-stream and repeatedly decodes them without progress. The issue occurs when an untrusted server sends a chunked Deflate response whose decoded body exceeds a positive finite chunk size and whose encoded body has

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 78%)
CISA exploited list	No
Weakness	CWE-835
Published	2026-09-29
Last modified	2026-10-13

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

Last updated 2026-10-13 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-29 16:17 UTCPublished CVE record published
2026-10-13 20:21 UTCUpdated Record last modified

python urllib3 UPGRADE

Affected: >= 2.6.2 and < 2.8.0

Fixed in: 2.8.0

Safe to downgrade to: a release before 2.6.2

1. Check installed version

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

2. UPGRADE to 2.8.0 (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 2.6.2 (Debian / Ubuntu)

apt-cache madison urllib3 sudo apt install urllib3=<VERSION_BEFORE_2.6.2> 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_2.6.2> 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.

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-2026-97688?

urllib3: upgrade to 2.8.0. Exact commands for each OS are on this page.

Is CVE-2026-97688 being exploited?

CVE-2026-97688 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-2026-97688 affect?

CVE-2026-97688 affects urllib3. Severity is medium (CVSS 5.3). urllib3 is an HTTP client library for Python. From 2.6.2 until 2.8.0, HTTPResponse.stream and HTTPResponse.read_chunked can enter an infinite loop because the Deflate decoder retains trailing bytes as unconsumed input after reaching end-of-

How urgent is CVE-2026-97688?

Priority 29/100. 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-2026-97689 HIGH 7.5 UPGRADE urllib3 is an HTTP client library for Python

References

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