Vulnerability Details 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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.003
EPSS Ranking 20.1%
CVSS Severity
CVSS v3 Score 7.5
References
Products affected by CVE-2026-97689
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cpe:2.3:a:python:urllib3:1.10.3
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cpe:2.3:a:python:urllib3:1.10.4
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cpe:2.3:a:python:urllib3:1.11
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cpe:2.3:a:python:urllib3:1.12
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cpe:2.3:a:python:urllib3:1.13
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cpe:2.3:a:python:urllib3:1.13.1
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cpe:2.3:a:python:urllib3:1.14
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cpe:2.3:a:python:urllib3:1.15
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cpe:2.3:a:python:urllib3:1.15.1
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cpe:2.3:a:python:urllib3:1.16
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cpe:2.3:a:python:urllib3:1.17
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cpe:2.3:a:python:urllib3:1.18
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cpe:2.3:a:python:urllib3:1.18.1
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cpe:2.3:a:python:urllib3:1.19
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cpe:2.3:a:python:urllib3:1.19.1
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cpe:2.3:a:python:urllib3:1.20
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cpe:2.3:a:python:urllib3:1.21
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cpe:2.3:a:python:urllib3:1.21.1
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cpe:2.3:a:python:urllib3:1.22
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cpe:2.3:a:python:urllib3:1.23
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cpe:2.3:a:python:urllib3:1.24
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cpe:2.3:a:python:urllib3:1.24.1
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cpe:2.3:a:python:urllib3:1.24.2
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cpe:2.3:a:python:urllib3:1.24.3
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cpe:2.3:a:python:urllib3:1.25
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cpe:2.3:a:python:urllib3:1.25.1
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cpe:2.3:a:python:urllib3:1.25.10
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cpe:2.3:a:python:urllib3:1.25.11
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cpe:2.3:a:python:urllib3:1.25.2
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cpe:2.3:a:python:urllib3:1.25.3
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cpe:2.3:a:python:urllib3:1.25.4
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cpe:2.3:a:python:urllib3:1.25.5
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cpe:2.3:a:python:urllib3:1.25.6
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cpe:2.3:a:python:urllib3:1.25.7
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cpe:2.3:a:python:urllib3:1.25.8
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cpe:2.3:a:python:urllib3:1.25.9
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cpe:2.3:a:python:urllib3:1.26.0
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cpe:2.3:a:python:urllib3:1.26.1
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cpe:2.3:a:python:urllib3:1.26.10
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cpe:2.3:a:python:urllib3:1.26.11
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cpe:2.3:a:python:urllib3:1.26.12
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cpe:2.3:a:python:urllib3:1.26.13
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cpe:2.3:a:python:urllib3:1.26.14
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cpe:2.3:a:python:urllib3:1.26.15
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cpe:2.3:a:python:urllib3:1.26.16
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cpe:2.3:a:python:urllib3:1.26.17
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cpe:2.3:a:python:urllib3:1.26.18
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cpe:2.3:a:python:urllib3:1.26.19
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cpe:2.3:a:python:urllib3:1.26.2
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cpe:2.3:a:python:urllib3:1.26.20
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cpe:2.3:a:python:urllib3:1.26.3
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cpe:2.3:a:python:urllib3:1.26.4
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cpe:2.3:a:python:urllib3:1.26.5
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cpe:2.3:a:python:urllib3:1.26.6
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cpe:2.3:a:python:urllib3:1.26.7
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cpe:2.3:a:python:urllib3:1.26.8
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cpe:2.3:a:python:urllib3:1.26.9
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cpe:2.3:a:python:urllib3:2.0.0
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cpe:2.3:a:python:urllib3:2.0.0a1
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cpe:2.3:a:python:urllib3:2.0.0a2
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cpe:2.3:a:python:urllib3:2.0.0a3
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cpe:2.3:a:python:urllib3:2.0.0a4
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cpe:2.3:a:python:urllib3:2.0.1
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cpe:2.3:a:python:urllib3:2.0.2
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cpe:2.3:a:python:urllib3:2.0.3
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cpe:2.3:a:python:urllib3:2.0.4
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cpe:2.3:a:python:urllib3:2.0.5
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cpe:2.3:a:python:urllib3:2.0.6
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cpe:2.3:a:python:urllib3:2.0.7
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cpe:2.3:a:python:urllib3:2.1.0
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cpe:2.3:a:python:urllib3:2.2.0
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cpe:2.3:a:python:urllib3:2.2.1
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cpe:2.3:a:python:urllib3:2.2.2
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cpe:2.3:a:python:urllib3:2.2.3
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cpe:2.3:a:python:urllib3:2.3.0
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cpe:2.3:a:python:urllib3:2.4.0
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cpe:2.3:a:python:urllib3:2.5.0
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cpe:2.3:a:python:urllib3:2.6.0
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cpe:2.3:a:python:urllib3:2.6.1
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cpe:2.3:a:python:urllib3:2.7.0