CVE-2021-23336: Debian Linux

Medium severity, CVSS 5.9. EPSS: 40.7% chance of exploitation in the next 30 days.

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 products

• Debian Debian Linux: version 9.0 only
• Djangoproject Django: from 2.2, before 2.2.19 (fixed in 2.2.19); from 3.0, before 3.0.13 (fixed in 3.0.13); from 3.1, before 3.1.7 (fixed in 3.1.7)
• Fedoraproject Fedora: version 32 only; version 33 only; version 34 only
• Netapp Cloud Backup: affected versions not specified
• Netapp Inventory Collect Tool: affected versions not specified
• Netapp Ontap Select Deploy Administration Utility: affected versions not specified
• Netapp Snapcenter: affected versions not specified
• Oracle Communications Offline Mediation Controller: version 12.0.0.3.0 only
• Oracle Communications Pricing Design Center: version 12.0.0.3.0 only
• Oracle Enterprise Manager Ops Center: version 12.4.0.0 only
• Oracle ZFS Storage Appliance: version 8.8 only
• Python Python: before 3.6.13 (fixed in 3.6.13); from 3.7.0, before 3.7.10 (fixed in 3.7.10); from 3.8.0, before 3.8.8 (fixed in 3.8.8); from 3.9.0, before 3.9.2 (fixed in 3.9.2)

Published 2021-02-15. Last modified 2026-06-17.