CVE-2026-97688

python-urllib3: urllib3 is an HTTP client library for Python

CVE-2026-97688 is fixed in 3 products on 1 platform, first by python3-urllib3 2.6.3-1ubuntu1.2, released September 29, 2026. It is not reported as exploited. Patch Radar priority: Routine.

Routine
CVSS
5.3
medium
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0029
21st percentile

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 trailing bytes, specifically a response with Transfer-Encoding: chunked and Content-Encoding: deflate, content decoding enabled, and the positive finite amt=N streaming chunk size. The attack mechanism is that a malicious server returns a compressed chunked response with trailing bytes after the Deflate stream. The impact is excessive CPU usage and a request that does not complete, and network read timeouts do not interrupt the loop because no further socket read occurs. This issue is fixed in version 2.8.0.

Where it's fixed

ProductFixed inFixReleased
Linux
python-urllib3 · Debian 14 2.8.0-1 DEBIAN-CVE-2026-97688 Sep 30, 2026
python-urllib3 · opensuse-leap 16.0 2.5.0-160000.8.1 OPENSUSE-SU-2026:22071-1 Nov 7, 2026
python-urllib3 · sles 15.6 2.0.7-150400.7.36.1 SUSE-SU-2026:4704-1 Nov 7, 2026
python-urllib3 · sles 15.7 2.0.7-150400.7.36.1 SUSE-SU-2026:4704-1 Nov 7, 2026
python-urllib3 · sles 16.0 2.5.0-160000.8.1 SUSE-SU-2026:24217-1 Nov 7, 2026
python-urllib3_1 · sles 15.6 1.26.18-150600.3.14.1 SUSE-SU-2026:4948-1 Nov 7, 2026
python-urllib3_1 · sles 15.7 1.26.18-150600.3.14.1 SUSE-SU-2026:4948-1 Nov 7, 2026
python3-urllib3 · Ubuntu 26.04.1 LTS (resolute) 2.6.3-1ubuntu1.2 python3-urllib3 2.6.3-1ubuntu1.2 Sep 29, 2026

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