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osvGoogleOSV:CVE-2021-23336
HistoryFeb 15, 2021 - 1:15 p.m.

CVE-2021-23336

2021-02-1513:15:12
Google
osv.dev
9
web cache poisoning
urllib.parse.parse_qsl
urllib.parse.parse_qs
parameter cloaking
proxy
server
cache key

AI Score

6

Confidence

High

EPSS

0.001

Percentile

49.9%

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.

References