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CVE-2021-41773

Path traversal and file disclosure vulnerability in Apache HTTP Server 2.4.49

High7.5Known exploitedPublic exploitEPSS 100.0%
Published
Updated
Reserved
Assigned by
apache

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.

Exploited in the wild

CISA lists this vulnerability in its Known Exploited Vulnerabilities catalog as Apache HTTP Server Path Traversal Vulnerability.

Added
3 Nov 2021
Fix due (US federal)
17 Nov 2021
Used by ransomware
Known

Apply updates per vendor instructions.

Public exploit

An exploit or proof of concept is public: anyone can try it against an unpatched system. CISA's SSVC rates its exploitation: it is being exploited.

Timeline

  1. ID reserved

    By apache

  2. · 6 days later

    Published

  3. · 29 days later

    Added to CISA KEV

    Known exploited, also by ransomware

  4. · 4 years later

    Record updated

Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.

Scores

CVSS scores of CVE-2021-41773, by who scored it
Scored byCVSSScoreVector
CISA-ADPADP (enrichment)3.1High7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
NVDNVD · Analyzed3.1Critical9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (exploitation in 30 days)
100.0% · top 0.1% of all CVEs (7 Nov 2026)
CISA SSVC
Exploitation: active · Automatable: yes · Technical impact: total
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.

Weakness

Affected products

References (30)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .