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Findings

CVE-2021-23336

The package python/cpython from 0 and before 3.6.13, from 3.7.0 and before 3.7.10, from 3.8.0 and before 3.8.8, from 3.9.0 and before 3.9.2 are vulnerable to Web Cache…

Published Feb 15, 2021 · updated Oct 14, 2026 · python python

The package python/cpython from 0 and before 3.6.13, from 3.7.0 and before 3.7.10, from 3.8.0 and before 3.8.8, from 3.9.0 and before 3.9.2 are vulnerable to Web Cache Poisoning via urllib.parse.parse_qsl and urllib.parse.parse_qs by using a vector called parameter cloaking. When the attacker can separate query parameters using a semicolon (;), they can cause a difference in the interpretation of the request between the proxy (running with default configuration) and the server. This can result in malicious requests being cached as completely safe ones, as the proxy would usually not see the semicolon as a separator, and therefore would not include it in a cache key of an unkeyed parameter.

Timeline

Detection, updates, and resolution for this record.

  1. Feb 15, 2021 · NIST NVD

    Detected

    The package python/cpython from 0 and before 3.6.13, from 3.7.0 and before 3.7.10, from 3.8.0 and before 3.8.8, from 3.9.0 and before 3.9.2 are vulnerable to Web Cache Poisoning via urllib.parse.parse_qsl and urllib.parse.parse_qs by using a vector called parameter cloaking. When the attacker can separate query parameters using a semicolon (;), they can cause a difference in the interpretation of

  2. Oct 14, 2026 · NIST NVD

    Updated

    The package python/cpython from 0 and before 3.6.13, from 3.7.0 and before 3.7.10, from 3.8.0 and before 3.8.8, from 3.9.0 and before 3.9.2 are vulnerable to Web Cache Poisoning via urllib.parse.parse_qsl and urllib.parse.parse_qs by using a vector called parameter cloaking. When the attacker can separate query parameters using a semicolon (;), they can cause a difference in the interpretation of

Affected

  • cpe debian/debian linux9.0
  • cpe djangoproject/djangoversion unspecified
  • cpe fedoraproject/fedora32
  • cpe fedoraproject/fedora33
  • cpe fedoraproject/fedora34
  • cpe netapp/cloud backupversion unspecified
  • cpe oracle/communications offline mediation controller12.0.0.3.0
  • cpe python/pythonversion unspecified

Sources

  • CVE.orgCVE-2021-23336

    Official CVE identifier

    cve.org
  • NIST NVDCVE-2021-23336

    The package python/cpython from 0 and before 3.6.13, from 3.7.0 and before 3.7.10, from 3.8.0 and before 3.8.8, from 3.9.0 and before 3.9.2 are vulnerable to Web Cache Poisoning via urllib.parse.parse_qsl and urllib.parse.parse_qs by using a vector called parameter cloaking. When

    nvd.nist.gov

References