CVE-2021-23336

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.

How to fix CVE-2021-23336

To remediate CVE-2021-23336, upgrade the affected package to a fixed version below.

—upgrade to 3.8.8-r0 or later
—upgrade to 2.2.19 or later
—upgrade to 3.6.13 or later
—upgrade to 3.6.13 or later
—upgrade to 3.6.13 or later
—upgrade to 7.3.3+dfsg-3 or later
—upgrade to 2.7.18-8+deb11u1 or later
—upgrade to 2.7.16-2+deb10u3 or later
—upgrade to 3.5.3-1+deb9u4 or later
—upgrade to 3.9.2-1 or later
—upgrade to 2:2.2.19-1 or later
—upgrade to 1:1.10.7-2+deb9u11 or later

Is CVE-2021-23336 being exploited?

Low — EPSS is 0.3%, meaning exploitation activity has not been observed at scale.

Affected packages (12)

from 0, < 3.8.8-r0
>= 2.2.0, < 2.2.19, >= 3.0.0, < 3.0.13, >= 3.1.0, < 3.1.7
from 0, < 3.6.13, >= 3.7.0, < 3.7.10, >= 3.8.0, < 3.8.8, >= 3.9.0, < 3.9.2
from 0, < 3.6.13, >= 3.7.0, < 3.7.10, >= 3.8.0, < 3.8.8, >= 3.9.0, < 3.9.2
from 0, < 3.6.13, >= 3.7.0, < 3.7.10, >= 3.8.0, < 3.8.8, >= 3.9.0, < 3.9.2
from 0, < 7.3.3+dfsg-3
from 0, < 2.7.18-8+deb11u1
from 0, < 2.7.16-2+deb10u3
from 0, < 3.5.3-1+deb9u4
from 0, < 3.9.2-1

CVSS scores

Source	Version	Severity	Vector
osv	CVSS 3.1	MEDIUM5.9	CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:H