CVE-2026-97689
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.
- Score
- CVSS 4.0 8.9 High
- Status
- Analyzed - security-advisories@github.com
- Published
- 2026-09-29
- Last modified
- 2026-10-13
- Weaknesses
- CWE-770
Affected products
References
- https://github.com/urllib3/urllib3/security/advisories/GHSA-vxq7-64xx-v4gw
- https://github.com/urllib3/urllib3/commit/cd770b059b543be29298ea5c52afb0b1b090f5ed
- https://github.com/urllib3/urllib3/releases/tag/2.8.0
