[ CVE-2026-97689 · Published 29 Sep 2026 ]
urllib3: HTTPResponse.stream()/read_chunked() buffers an unbounded chunk-size line into memory
[ Description ]Official description
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 server sends a very long unterminated chunk-size line. The impact is that unbounded memory allocation can exhaust the client process. This issue is fixed in version 2.8.0.
[ Fixes ]Fixes and patches
- urllib3 2.8.0Fixed version · GitHub Advisories · pip package urllib3: upgrade to 2.8.0 or later (affected >= 1.10.3, < 2.8.0)
- Patch on github.comVendor patch or bulletin · NVD · Reference tagged 'Patch' by NVD
[ Advisories ]Government CERT advisories
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BSI CERT-BundWID-SEC-2026-4111
Red Hat Ansible Automation Platform: Multiple vulnerabilities Translated from German
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BSI CERT-BundWID-SEC-2026-4024
Red Hat Quay and Enterprise Linux (pypdf, urllib3, URI): Multiple vulnerabilities Translated from German
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CERT-FRCERTFR-2026-AVI-1249
Multiple vulnerabilities in VMware products Translated from French
Multiple vulnerabilities have been discovered in VMware products. They allow an attacker to cause a security problem not specified by the vendor.
[ Packages ]Affected open-source packages
- urllib3 pipAffected >= 1.10.3, < 2.8.0 · fixed in 2.8.0 · GHSA-vxq7-64xx-v4gw