CVE-2021-41773

CRITICAL severity · CVSS 9.8 · Path traversal · actively exploited (CISA KEV)

9.8CVSS CRITICAL ● exploited ⚠ ransomware

🔴 Actively exploited in the wild (CISA Known Exploited Vulnerabilities). ⚠ Known use in ransomware campaigns. Added to KEV 2021-11-03. US federal agencies must patch by 2021-11-17.

Summary

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.

Impact & exploitability

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

Confidentiality impactHigh

Integrity impactHigh

Availability impactHigh

Exploit probability (EPSS)94%

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products we track (1)

Apache HTTP Server

Recommendation

This vulnerability is being actively exploited in the wild — patch affected products urgently. Open any affected product above for its exact safe version.

CVE-2021-41773

Summary

Impact & exploitability

Affected products we track (1)

Recommendation

Additional information