CVE-2021-23336: Web Cache Poisoning

Vulnerability summary

CVE-2021-23336 is a medium (CVSS 5.9) vulnerability in debian debian_linux. EPSS estimates a 40.74% chance of exploitation in the next 30 days, higher than 98.6% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 15-02-2021
   PublishedVulnerability first disclosed.
2. 14-10-2026
   Last modifiedVulnerability information updated.

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.

• CWE-444Inconsistent Interpretation of HTTP RequestsThe product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.