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.
Advisories
Source ID Title
Debian DLA Debian DLA DLA-2569-1 python-django security update
Debian DLA Debian DLA DLA-2619-1 python3.5 security update
Debian DLA Debian DLA DLA-2628-1 python2.7 security update
Debian DLA Debian DLA DLA-3164-1 python-django security update
Debian DLA Debian DLA DLA-3575-1 python2.7 security update
EUVD EUVD EUVD-2021-10423 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.
Ubuntu USN Ubuntu USN USN-4742-1 Django vulnerability
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

References
Link Providers
http://www.openwall.com/lists/oss-security/2021/02/19/4 cve-icon cve-icon
http://www.openwall.com/lists/oss-security/2021/05/01/2 cve-icon cve-icon
https://github.com/python/cpython/pull/24297 cve-icon cve-icon
https://lists.apache.org/thread.html/ra8ce70088ba291f358e077cafdb14d174b7a1ce9a9d86d1b332d6367%40%3Cusers.airflow.apache.org%3E cve-icon cve-icon
https://lists.apache.org/thread.html/rc005f4de9d9b0ba943ceb8ff5a21a5c6ff8a9df52632476698d99432%40%3Cannounce.apache.org%3E cve-icon cve-icon
https://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3E cve-icon cve-icon
https://lists.debian.org/debian-lts-announce/2021/02/msg00030.html cve-icon cve-icon
https://lists.debian.org/debian-lts-announce/2021/04/msg00005.html cve-icon cve-icon
https://lists.debian.org/debian-lts-announce/2021/04/msg00015.html cve-icon cve-icon
https://lists.debian.org/debian-lts-announce/2023/09/msg00022.html cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3EPYWWFDV22CJ5AOH5VCE72DOASZZ255/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3YKKDLXL3UEZ3J426C2XTBS63AHE46SM/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/46N6A52EGSXHJYCZWVMBJJIH4NWIV2B5/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FONHJIOZOFD7CD35KZL6SVBUTMBPGZGA/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HCQTCSP6SCVIYNIRUJC5X7YBVUHPLSC4/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HZTM7KLHFCE3LWSEVO2NAFLUHMGYMCRY/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IHQDU7NXA7EWAE4W7VO6MURVJIULEPPR/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KJXCMHLY7H3FIYLE4OKDYUILU2CCRUCZ/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LVNH6Z24IG3E67ZCQGGJ46FZB4XFLQNZ/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MNUN5SOMFL2BBKP6ZAICIIUPQKZDMGYO/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MP572OLHMS7MZO4KUPSCIMSZIA5IZZ62/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/N6VXJZSZ6N64AILJX4CTMACYGQGHHD5C/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NJSCSN722JO2E2AGPWD4NTGVELVRPB4R/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NODWHDIFBQE5RU5PUWUVE47JOT5VCMJ2/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OAGSWNGZJ6HQ5ISA67SNMK3CJRKICET7/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RSLQD5CCM75IZGAMBDGUZEATYU5YSGJ7/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SGIY6I4YS3WOXAK4SXKIEOC2G4VZKIR7/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TFTELUMWZE3KV3JB2H5EE6VFRZFRD5MV/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/W2LSKBEFI5SYEY5FM6ICZVZM5WRQUCS4/ cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2021-23336 cve-icon
https://security.gentoo.org/glsa/202104-04 cve-icon cve-icon
https://security.netapp.com/advisory/ntap-20210326-0004/ cve-icon cve-icon
https://snyk.io/blog/cache-poisoning-in-popular-open-source-packages/ cve-icon cve-icon
https://snyk.io/vuln/SNYK-UPSTREAM-PYTHONCPYTHON-1074933 cve-icon cve-icon cve-icon
https://www.cve.org/CVERecord?id=CVE-2021-23336 cve-icon
https://www.oracle.com//security-alerts/cpujul2021.html cve-icon cve-icon
https://www.oracle.com/security-alerts/cpuApr2021.html cve-icon cve-icon
https://www.oracle.com/security-alerts/cpujan2022.html cve-icon cve-icon
https://www.oracle.com/security-alerts/cpuoct2021.html cve-icon cve-icon
History

Wed, 17 Dec 2025 22:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: snyk

Published:

Updated: 2025-12-17T21:16:09.153Z

Reserved: 2021-01-08T00:00:00.000Z

Link: CVE-2021-23336

cve-icon Vulnrichment

Updated: 2024-08-03T19:05:55.612Z

cve-icon NVD

Status : Modified

Published: 2021-02-15T13:15:12.433

Modified: 2025-12-17T22:15:55.923

Link: CVE-2021-23336

cve-icon Redhat

Severity : Moderate

Publid Date: 2021-02-13T00:00:00Z

Links: CVE-2021-23336 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses