{"id":"CVE-2021-23336","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-23336","generatedAt":"2026-11-05T01:44:09.866Z","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 using a vector…","description":"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.","published":"2021-02-15T13:15:12.000Z","lastModified":"2026-10-14T12:17:09.000Z","status":"Modified","sourceIdentifier":"report@snyk.io","cvss":{"version":"3.1","score":5.9,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:H"},"cwe":["CWE-444"],"affected":["python/python","fedoraproject/fedora","debian/debian linux","netapp/cloud backup","netapp/inventory collect tool","netapp/ontap select deploy administration utility","netapp/snapcenter","djangoproject/django","oracle/communications offline mediation controller","oracle/communications pricing design center","oracle/enterprise manager ops center","oracle/zfs storage appliance"],"epss":{"score":0.40736,"percentile":0.98655,"date":"2026-11-03","history":[{"date":"2026-09-22","score":0.40736,"percentile":0.9859}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"urgent","text":"EPSS puts the probability of exploitation in the next 30 days at 40.7%, higher than 99% of all known CVEs. Patch or mitigate before the next change window."},"changes":[],"references":[{"url":"http://www.openwall.com/lists/oss-security/2021/02/19/4","tags":["Mailing List","Patch","Third Party Advisory"],"source":"report@snyk.io"},{"url":"http://www.openwall.com/lists/oss-security/2021/05/01/2","tags":["Mailing List","Third Party Advisory"],"source":"report@snyk.io"},{"url":"https://github.com/python/cpython/pull/24297","tags":["Patch","Third Party Advisory"],"source":"report@snyk.io"},{"url":"https://lists.apache.org/thread.html/ra8ce70088ba291f358e077cafdb14d174b7a1ce9a9d86d1b332d6367%40%3Cusers.airflow.apache.org%3E","source":"report@snyk.io"},{"url":"https://lists.apache.org/thread.html/rc005f4de9d9b0ba943ceb8ff5a21a5c6ff8a9df52632476698d99432%40%3Cannounce.apache.org%3E","source":"report@snyk.io"},{"url":"https://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3E","source":"report@snyk.io"},{"url":"https://lists.debian.org/debian-lts-announce/2021/02/msg00030.html","tags":["Mailing List","Third Party Advisory"],"source":"report@snyk.io"},{"url":"https://lists.debian.org/debian-lts-announce/2021/04/msg00005.html","tags":["Mailing List","Third Party Advisory"],"source":"report@snyk.io"},{"url":"https://lists.debian.org/debian-lts-announce/2021/04/msg00015.html","tags":["Mailing List","Third Party Advisory"],"source":"report@snyk.io"},{"url":"https://lists.debian.org/debian-lts-announce/2023/09/msg00022.html","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3EPYWWFDV22CJ5AOH5VCE72DOASZZ255/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3YKKDLXL3UEZ3J426C2XTBS63AHE46SM/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/46N6A52EGSXHJYCZWVMBJJIH4NWIV2B5/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FONHJIOZOFD7CD35KZL6SVBUTMBPGZGA/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HCQTCSP6SCVIYNIRUJC5X7YBVUHPLSC4/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HZTM7KLHFCE3LWSEVO2NAFLUHMGYMCRY/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IHQDU7NXA7EWAE4W7VO6MURVJIULEPPR/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KJXCMHLY7H3FIYLE4OKDYUILU2CCRUCZ/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LVNH6Z24IG3E67ZCQGGJ46FZB4XFLQNZ/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MNUN5SOMFL2BBKP6ZAICIIUPQKZDMGYO/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MP572OLHMS7MZO4KUPSCIMSZIA5IZZ62/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/N6VXJZSZ6N64AILJX4CTMACYGQGHHD5C/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NJSCSN722JO2E2AGPWD4NTGVELVRPB4R/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NODWHDIFBQE5RU5PUWUVE47JOT5VCMJ2/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OAGSWNGZJ6HQ5ISA67SNMK3CJRKICET7/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RSLQD5CCM75IZGAMBDGUZEATYU5YSGJ7/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SGIY6I4YS3WOXAK4SXKIEOC2G4VZKIR7/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TFTELUMWZE3KV3JB2H5EE6VFRZFRD5MV/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/W2LSKBEFI5SYEY5FM6ICZVZM5WRQUCS4/","source":"report@snyk.io"},{"url":"https://security.gentoo.org/glsa/202104-04","tags":["Third Party Advisory"],"source":"report@snyk.io"},{"url":"https://security.netapp.com/advisory/ntap-20210326-0004/","tags":["Third Party Advisory"],"source":"report@snyk.io"},{"url":"https://snyk.io/blog/cache-poisoning-in-popular-open-source-packages/","tags":["Technical Description","Third Party Advisory"],"source":"report@snyk.io"},{"url":"https://snyk.io/vuln/SNYK-UPSTREAM-PYTHONCPYTHON-1074933","tags":["Exploit","Third Party Advisory"],"source":"report@snyk.io"},{"url":"https://www.oracle.com//security-alerts/cpujul2021.html","tags":["Patch","Third Party Advisory"],"source":"report@snyk.io"},{"url":"https://www.oracle.com/security-alerts/cpuApr2021.html","tags":["Patch","Third Party Advisory"],"source":"report@snyk.io"},{"url":"https://www.oracle.com/security-alerts/cpujan2022.html","tags":["Patch","Third Party Advisory"],"source":"report@snyk.io"},{"url":"https://www.oracle.com/security-alerts/cpuoct2021.html","tags":["Patch","Third Party Advisory"],"source":"report@snyk.io"},{"url":"http://www.openwall.com/lists/oss-security/2021/02/19/4","tags":["Mailing List","Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.openwall.com/lists/oss-security/2021/05/01/2","tags":["Mailing List","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/python/cpython/pull/24297","tags":["Patch","Third Party 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Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2021/04/msg00015.html","tags":["Mailing List","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2023/09/msg00022.html","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3EPYWWFDV22CJ5AOH5VCE72DOASZZ255/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3YKKDLXL3UEZ3J426C2XTBS63AHE46SM/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/46N6A52EGSXHJYCZWVMBJJIH4NWIV2B5/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FONHJIOZOFD7CD35KZL6SVBUTMBPGZGA/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HCQTCSP6SCVIYNIRUJC5X7YBVUHPLSC4/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HZTM7KLHFCE3LWSEVO2NAFLUHMGYMCRY/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IHQDU7NXA7EWAE4W7VO6MURVJIULEPPR/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KJXCMHLY7H3FIYLE4OKDYUILU2CCRUCZ/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LVNH6Z24IG3E67ZCQGGJ46FZB4XFLQNZ/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MNUN5SOMFL2BBKP6ZAICIIUPQKZDMGYO/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MP572OLHMS7MZO4KUPSCIMSZIA5IZZ62/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/N6VXJZSZ6N64AILJX4CTMACYGQGHHD5C/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NJSCSN722JO2E2AGPWD4NTGVELVRPB4R/","source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-23336","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}