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CVE-2026-97689: urllib3 is an HTTP client library for Python

38
Routine
HIGH 7.5REMOTEUPGRADE

CVE-2026-97689 is a high-severity flaw (CVSS 7.5) 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 1.10.3 until 2.8.0, the HTTPResponse.read_chunked and HTTPResponse.stream methods can allocate unbounded memory because the streaming chunk parser buffers the chunk-size field until newline or EOF without a length bound. The trigger is that a malicious server returns Transfer-Encoding: chunked followed by a very long run of bytes without a newline. The attack mechanism is that a malicious HTTP se

Why this priority

  • High severity
  • Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score7.5 (High)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance0.3% (top 73%)
CISA exploited listNo
WeaknessCWE-770
Published2026-09-29
Last modified2026-10-13
Publisher (CNA): GitHub, Inc. · Vendor: python

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

Am I affected?

Timeline

python urllib3 UPGRADE
Affected: >= 1.10.3 and < 2.8.0
Fixed in: 2.8.0
Safe to downgrade to: a release before 1.10.3
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 1.10.3 (Debian / Ubuntu)
apt-cache madison urllib3 sudo apt install urllib3=<VERSION_BEFORE_1.10.3> 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_1.10.3> 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

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-2026-97689?

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

Is CVE-2026-97689 being exploited?

CVE-2026-97689 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-2026-97689 affect?

CVE-2026-97689 affects urllib3. Severity is high (CVSS 7.5). urllib3 is an HTTP client library for Python. From 1.10.3 until 2.8.0, the HTTPResponse.read_chunked and HTTPResponse.stream methods can allocate unbounded memory because the streaming chunk parser buffers the chunk-size field until newline

How urgent is CVE-2026-97689?

Priority 38/100. High severity; Remotely exploitable, no login, no user action

Software pages

Python vulnerabilities

Related CVEs

References

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