Apache HTTP Server Path Traversal Vulnerability
It was found that the fix for CVE-2021-41773 in Apache HTTP Server 2.4.50 was insufficient. 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…
Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.
Exploitation probability EPSS · FIRST
Exploitation signals 5 / 5
- KEV catalog (CISA)03 Nov 2021
- Exploited in EUVD (ENISA)03 Nov 2021
- Used by ransomwareyes
- EPSS above 10 %99.96%
- No account, over the networkyes
What to do
Fix
Update to a fixed version: 2.4.51-1
CISA guidance: Apply updates per vendor instructions.
Meanwhile
Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.
Manufacturers (CRA)
Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained
Description ENISA EUVD
It was found that the fix for CVE-2021-41773 in Apache HTTP Server 2.4.50 was insufficient. 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 only affects Apache 2.4.49 and Apache 2.4.50 and not earlier versions.
Affected products
- Apache HTTP Server 2.4.50
- Apache HTTP Server 2.4.49
Open source packages OSV
- apache2Debian:13 · CVE-2021-42013fixed in 2.4.51-1
Timeline
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Published
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Exploitation reported (ENISA)
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Added to the KEV catalog
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CISA remediation due date
-
EPSS peak: 99.96%
References
Other exploited vulnerabilities from the same vendor
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- CVE-2025-24813Apache Tomcat Path Equivalence Vulnerability9.4 · Background exploitation
- CVE-2024-45195Apache OFBiz Forced Browsing Vulnerability9.3 · Background exploitation