CVE-2021-41773 KEV EXPLOIT
Patch first
On CISA KEV — known exploited in the wild, due 2021-11-17.
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.
Scoring
| CVSS | 9.8 (CRITICAL, v3.1) |
|---|---|
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| EPSS | 99.99% — more likely to be exploited than 100% of all CVEs |
| Weakness | CWE-22 |
| On CISA KEV | yes — remediate by 2021-11-17 |
| Public exploit | yes |
| Published | 2021-10-05 |
| Last modified | 2026-06-17 |
CISA KEV
| Name | Apache HTTP Server Path Traversal Vulnerability |
|---|---|
| Added | 2021-11-03 |
| Due | 2021-11-17 |
| Vendor / product | Apache / HTTP Server |
| Ransomware use | known |
Affected (4)
| Vendor | Product |
|---|---|
| apache | http server |
| fedoraproject | fedora |
| netapp | cloud backup |
| oracle | instantis enterprisetrack |
Public exploits
| Source | Title | Date |
|---|---|---|
| exploit-db | Apache HTTP Server 2.4.50 - Remote Code Execution (RCE) (3) | 2021-11-11 |
| exploit-db | Apache HTTP Server 2.4.49 - Path Traversal & Remote Code Execution (RCE) | 2021-10-06 |
References
- http://packetstormsecurity.com/files/164418/Apache-HTTP-Server-2.4.49-Path-Traversal-Remote-Code-Execution.html
- http://packetstormsecurity.com/files/164418/Apache-HTTP-Server-2.4.49-Path-Traversal.html
- http://packetstormsecurity.com/files/164629/Apache-2.4.49-2.4.50-Traversal-Remote-Code-Execution.html
- http://packetstormsecurity.com/files/164941/Apache-HTTP-Server-2.4.50-Remote-Code-Execution.html
- http://www.openwall.com/lists/oss-security/2021/10/05/2
- http://www.openwall.com/lists/oss-security/2021/10/07/1
- http://www.openwall.com/lists/oss-security/2021/10/07/6
- http://www.openwall.com/lists/oss-security/2021/10/08/1
- http://www.openwall.com/lists/oss-security/2021/10/08/2
- http://www.openwall.com/lists/oss-security/2021/10/08/3
- http://www.openwall.com/lists/oss-security/2021/10/08/4
- http://www.openwall.com/lists/oss-security/2021/10/08/5
- http://www.openwall.com/lists/oss-security/2021/10/08/6
- http://www.openwall.com/lists/oss-security/2021/10/09/1
- http://www.openwall.com/lists/oss-security/2021/10/11/4
- http://www.openwall.com/lists/oss-security/2021/10/15/3
- http://www.openwall.com/lists/oss-security/2021/10/16/1
- https://httpd.apache.org/security/vulnerabilities_24.html
- https://lists.apache.org/thread.html/r17a4c6ce9aff662efd9459e9d1850ab4a611cb23392fc68264c72cb3%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/r6abf5f2ba6f1aa8b1030f95367aaf17660c4e4c78cb2338aee18982f%40%3Cusers.httpd.apache.org%3E
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