CVE-2021-41773

Description

A flaw was found in a change made to path normalization in Apache HTTP Server 2.4.49. An attacker could use a path traversal attack to map URLs to files outside the directories configured by Alias-like directives. If files outside of these directories are not protected by the usual default configuration "require all denied", these requests can succeed. If CGI scripts are also enabled for these aliased pathes, this could allow for remote code execution. This issue is known to be exploited in the wild. This issue only affects Apache 2.4.49 and not earlier versions. The fix in Apache HTTP Server 2.4.50 was found to be incomplete, see CVE-2021-42013.

How to fix CVE-2021-41773

To remediate CVE-2021-41773, upgrade the affected package to a fixed version below.

—upgrade to 2.4.50-r0 or later
—upgrade to 2.4.50 or later
—upgrade to 2.4.50-1 or later

Is CVE-2021-41773 being exploited?

Yes — CVE-2021-41773 is on the CISA Known Exploited Vulnerabilities (KEV) catalog. Patch immediately.

Affected packages (3)

from 0, < 2.4.50-r0
>= 2.4.49, < 2.4.50
from 0, < 2.4.50-1

CVSS scores

Source	Version	Severity	Vector
osv	CVSS 3.1	CRITICAL9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H