--- id: CVE-2021-23336 title: >- 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 usi… summary: >- 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 usi… severity: medium cvss: 5.9 cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:H' cwe: - CWE-444 - CWE-444 vendor: python product: python affected: - python < 3.6.13 - 'python >= 3.7.0, < 3.7.10' - 'python >= 3.8.0, < 3.8.8' - 'python >= 3.9.0, < 3.9.2' - fedora = 32 - fedora = 33 - fedora = 34 - debian_linux = 9.0 - cloud_backup - inventory_collect_tool - ontap_select_deploy_administration_utility - snapcenter - 'django >= 2.2, < 2.2.19' - 'django >= 3.0, < 3.0.13' - 'django >= 3.1, < 3.1.7' - communications_offline_mediation_controller = 12.0.0.3.0 - communications_pricing_design_center = 12.0.0.3.0 - enterprise_manager_ops_center = 12.4.0.0 - zfs_storage_appliance = 8.8 patched: - python 3.9.2 - django 3.1.7 published: '2021-02-15' updated: '2026-10-14' sourceUpdated: '2026-10-14T12:17:09.467' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-23336' references: - url: 'http://www.openwall.com/lists/oss-security/2021/02/19/4' label: report@snyk.io - url: 'http://www.openwall.com/lists/oss-security/2021/05/01/2' label: report@snyk.io - url: 'https://github.com/python/cpython/pull/24297' label: report@snyk.io - url: >- https://lists.apache.org/thread.html/ra8ce70088ba291f358e077cafdb14d174b7a1ce9a9d86d1b332d6367%40%3Cusers.airflow.apache.org%3E label: report@snyk.io - url: >- https://lists.apache.org/thread.html/rc005f4de9d9b0ba943ceb8ff5a21a5c6ff8a9df52632476698d99432%40%3Cannounce.apache.org%3E label: report@snyk.io - url: >- https://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3E label: report@snyk.io - url: 'https://lists.debian.org/debian-lts-announce/2021/02/msg00030.html' label: report@snyk.io - url: 'https://lists.debian.org/debian-lts-announce/2021/04/msg00005.html' label: report@snyk.io - url: 'https://lists.debian.org/debian-lts-announce/2021/04/msg00015.html' label: report@snyk.io - url: 'https://lists.debian.org/debian-lts-announce/2023/09/msg00022.html' label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3EPYWWFDV22CJ5AOH5VCE72DOASZZ255/ label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3YKKDLXL3UEZ3J426C2XTBS63AHE46SM/ label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/46N6A52EGSXHJYCZWVMBJJIH4NWIV2B5/ label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FONHJIOZOFD7CD35KZL6SVBUTMBPGZGA/ label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HCQTCSP6SCVIYNIRUJC5X7YBVUHPLSC4/ label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HZTM7KLHFCE3LWSEVO2NAFLUHMGYMCRY/ label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IHQDU7NXA7EWAE4W7VO6MURVJIULEPPR/ label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KJXCMHLY7H3FIYLE4OKDYUILU2CCRUCZ/ label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LVNH6Z24IG3E67ZCQGGJ46FZB4XFLQNZ/ label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MNUN5SOMFL2BBKP6ZAICIIUPQKZDMGYO/ label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MP572OLHMS7MZO4KUPSCIMSZIA5IZZ62/ label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/N6VXJZSZ6N64AILJX4CTMACYGQGHHD5C/ label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NJSCSN722JO2E2AGPWD4NTGVELVRPB4R/ label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NODWHDIFBQE5RU5PUWUVE47JOT5VCMJ2/ label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OAGSWNGZJ6HQ5ISA67SNMK3CJRKICET7/ label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RSLQD5CCM75IZGAMBDGUZEATYU5YSGJ7/ label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SGIY6I4YS3WOXAK4SXKIEOC2G4VZKIR7/ label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TFTELUMWZE3KV3JB2H5EE6VFRZFRD5MV/ label: report@snyk.io - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/W2LSKBEFI5SYEY5FM6ICZVZM5WRQUCS4/ label: report@snyk.io - url: 'https://security.gentoo.org/glsa/202104-04' label: report@snyk.io - url: 'https://security.netapp.com/advisory/ntap-20210326-0004/' label: report@snyk.io - url: 'https://snyk.io/blog/cache-poisoning-in-popular-open-source-packages/' label: report@snyk.io - url: 'https://snyk.io/vuln/SNYK-UPSTREAM-PYTHONCPYTHON-1074933' label: report@snyk.io - url: 'https://www.oracle.com//security-alerts/cpujul2021.html' label: report@snyk.io - url: 'https://www.oracle.com/security-alerts/cpuApr2021.html' label: report@snyk.io - url: 'https://www.oracle.com/security-alerts/cpujan2022.html' label: report@snyk.io - url: 'https://www.oracle.com/security-alerts/cpuoct2021.html' label: report@snyk.io - url: 'http://www.openwall.com/lists/oss-security/2021/02/19/4' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'http://www.openwall.com/lists/oss-security/2021/05/01/2' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://github.com/python/cpython/pull/24297' label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/ra8ce70088ba291f358e077cafdb14d174b7a1ce9a9d86d1b332d6367%40%3Cusers.airflow.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rc005f4de9d9b0ba943ceb8ff5a21a5c6ff8a9df52632476698d99432%40%3Cannounce.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3E label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://lists.debian.org/debian-lts-announce/2021/02/msg00030.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://lists.debian.org/debian-lts-announce/2021/04/msg00005.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://lists.debian.org/debian-lts-announce/2021/04/msg00015.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://lists.debian.org/debian-lts-announce/2023/09/msg00022.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3EPYWWFDV22CJ5AOH5VCE72DOASZZ255/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3YKKDLXL3UEZ3J426C2XTBS63AHE46SM/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/46N6A52EGSXHJYCZWVMBJJIH4NWIV2B5/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FONHJIOZOFD7CD35KZL6SVBUTMBPGZGA/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HCQTCSP6SCVIYNIRUJC5X7YBVUHPLSC4/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HZTM7KLHFCE3LWSEVO2NAFLUHMGYMCRY/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IHQDU7NXA7EWAE4W7VO6MURVJIULEPPR/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KJXCMHLY7H3FIYLE4OKDYUILU2CCRUCZ/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LVNH6Z24IG3E67ZCQGGJ46FZB4XFLQNZ/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MNUN5SOMFL2BBKP6ZAICIIUPQKZDMGYO/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MP572OLHMS7MZO4KUPSCIMSZIA5IZZ62/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/N6VXJZSZ6N64AILJX4CTMACYGQGHHD5C/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NJSCSN722JO2E2AGPWD4NTGVELVRPB4R/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NODWHDIFBQE5RU5PUWUVE47JOT5VCMJ2/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OAGSWNGZJ6HQ5ISA67SNMK3CJRKICET7/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RSLQD5CCM75IZGAMBDGUZEATYU5YSGJ7/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SGIY6I4YS3WOXAK4SXKIEOC2G4VZKIR7/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TFTELUMWZE3KV3JB2H5EE6VFRZFRD5MV/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/W2LSKBEFI5SYEY5FM6ICZVZM5WRQUCS4/ label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://security.gentoo.org/glsa/202104-04' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://security.netapp.com/advisory/ntap-20210326-0004/' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://snyk.io/blog/cache-poisoning-in-popular-open-source-packages/' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://snyk.io/vuln/SNYK-UPSTREAM-PYTHONCPYTHON-1074933' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://www.oracle.com//security-alerts/cpujul2021.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://www.oracle.com/security-alerts/cpuApr2021.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://www.oracle.com/security-alerts/cpujan2022.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://www.oracle.com/security-alerts/cpuoct2021.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://cert-portal.siemens.com/productcert/html/ssa-398330.html' label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e tags: - nvd epss: 0.40736 epssPercentile: 0.98628 ingestedAt: '2026-10-14T12:29:10.815Z' --- ## Overview 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. ## Affected - `python < 3.6.13` - `python >= 3.7.0, < 3.7.10` - `python >= 3.8.0, < 3.8.8` - `python >= 3.9.0, < 3.9.2` - `fedora = 32` - `fedora = 33` - `fedora = 34` - `debian_linux = 9.0` - `cloud_backup` - `inventory_collect_tool` - `ontap_select_deploy_administration_utility` - `snapcenter` - `django >= 2.2, < 2.2.19` - `django >= 3.0, < 3.0.13` - `django >= 3.1, < 3.1.7` - `communications_offline_mediation_controller = 12.0.0.3.0` - `communications_pricing_design_center = 12.0.0.3.0` - `enterprise_manager_ops_center = 12.4.0.0` - `zfs_storage_appliance = 8.8` ## Remediation Upgrade past the affected range: - `python 3.9.2` - `django 3.1.7`