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8.9 High

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

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.

Affected products and versions

Product Affected versions Fixed in
urllib3 1.10 1.10.3 → < 2.8.0 2.8.0

References

Timeline

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Other CVEs of urllib3

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