CVE-2021-41773
Apache Software Foundation Apache HTTP Server
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…
Published: 2021-10-05
Analysis
🟠 High — imminent exploitation
Weakness: Path Traversal (CWE-22). Accesses files outside the intended directory (../).
How it's exploited: Exploitable over the network (internet-reachable), unauthenticated, no user interaction, and with low complexity.
⚠️ Critical combo: remote, unauthenticated and no interaction → trivial to automate.
Impact: Full compromise (confidentiality, integrity and availability).
Status: Exploit probability (EPSS, 30 days): 100% — high.
- Apply the vendor patch according to risk priority.
- Reduce exposure: keep it off the internet; firewall, VPN or network segmentation.
- Detect: turn this CVE into detection rules.
MITRE ATT&CK technique: T1190 · Exploit Public-Facing Application
Practice it in the arsenal: WAF Bypass
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
The vector encodes how it's exploited (translated above, in the analysis). Break it down in the CVSS tool →
Sources: CISA KEV · EPSS · FIRST.org · NVD. Analysis derived from the CVSS vector and exploitation status (no AI). Informational; always verify against the vendor's official advisory.