CVE-2021-41773Path traversal and file disclosure vulnerability in Apache HTTP Server 2.4.49

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.

9.8 CRITICALEPSS 99.99%⚡ Known Exploited (CISA KEV)NVD: Analyzed

Last updated: 2026-06-17 04:08 UTC

OverviewCVSS details

9.8CRITICALCVSS 3.1

Score source: NVD
NVD status: Analyzed
Published: Oct 5, 2021
Assigner: apache

Affected

Apache HTTP Server (Apache Software Foundation)

Versions: Apache HTTP Server 2.4 2.4.49

Exploitation

Public exploit: Yes · 6 references
CISA KEV: Listed · Nov 3, 2021
KEV due date: Nov 17, 2021
Ransomware use: Known
SSVC: Exploitation active · Automatable yes · Impact total

EPSS · FIRST, scored Nov 8

99.99%chance of exploitation in 30 days

Higher than 99.98% of CVEs

CVSS 3.1 · NVD

9.8Critical

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

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

CVSS 3.1 · CISA-ADP

7.5High

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

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: None
Availability impact: None

CVSS 2.0 · NVD

4.3Medium

AV:N/AC:M/Au:N/C:P/I:N/A:N

Attack vector: Network
Attack complexity: Medium
Authentication: None
Confidentiality impact: Partial
Integrity impact: None
Availability impact: None

NVD status: Analyzed

Overview Affected Products References

NVD CVE.org

Overview

Severity

Score	Severity	Version	Vector String
9.8	CRITICAL	3.1NVD	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5	HIGH	3.1CISA-ADP	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
4.3	MEDIUM	2.0NVD	AV:N/AC:M/Au:N/C:P/I:N/A:N

CISA required action

⚡ Known exploited · remediation due Nov 17, 2021

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Details

CVE ID: CVE-2021-41773
Status: Analyzed
Assigner (CNA): apache
Published: Oct 5, 2021
Last modified: 2026-06-17 04:08 UTC
Weaknesses: CWE-22 · Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Sources

Refreshed hourly from the sources above. Last fetched 2026-11-09 12:15 UTC.