Apache · HTTP Server
CVE-2021-41773
Path traversal and file disclosure vulnerability in Apache HTTP Server 2.4.49
Qué es
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.
CISA: Apache HTTP Server contains a path traversal vulnerability that allows an attacker to perform remote code execution if files outside directories configured by Alias-like directives are not under default �require all denied� or if CGI scripts are enabled. The original patch issued under this CVE ID is insufficient, please review remediation information under CVE-2021-42013.
Qué hacer
Apply updates per vendor instructions.
Plazo para las agencias federales de EE. UU.: 17 de noviembre de 2021
- Añadida a la lista de CISA
- 3 de noviembre de 2021
- Publicada
- 5 de octubre de 2021
- Gravedad
- Alto 7,5 CVSS 3.1
- Probabilidad de ataques en los próximos 30 días (EPSS)
- >99,9% entre el 0,1% superior de todas las vulnerabilidades conocidas
- Debilidad
- CWE-22
- Más detalles
- NVD · CVE.org · CISA
Todas las referencias (20)
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-httpd-pathtrv-LAzg68cZ
- https://httpd.apache.org/security/vulnerabilities_24.html
- https://lists.apache.org/thread.html/r6abf5f2ba6f1aa8b1030f95367aaf17660c4e4c78cb2338aee18982f%40%3Cusers.htt…
- https://lists.apache.org/thread.html/r98d704ed4377ed889d40479db79ed1ee2f43b2ebdd79ce84b042df45%40%3Cannounce.…
- http://www.openwall.com/lists/oss-security/2021/10/05/2
- http://www.openwall.com/lists/oss-security/2021/10/07/1
- https://lists.apache.org/thread.html/r7c795cd45a3384d4d27e57618a215b0ed19cb6ca8eb070061ad5d837%40%3Cannounce.…
- https://lists.apache.org/thread.html/rb5b0e46f179f60b0c70204656bc52fcb558e961cb4d06a971e9e3efb%40%3Cusers.htt…
- http://www.openwall.com/lists/oss-security/2021/10/07/6
- http://www.openwall.com/lists/oss-security/2021/10/08/1
- https://lists.apache.org/thread.html/r17a4c6ce9aff662efd9459e9d1850ab4a611cb23392fc68264c72cb3%40%3Ccvs.httpd…
- 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/2021/10/08/6
- http://www.openwall.com/lists/oss-security/2021/10/08/5
- http://www.openwall.com/lists/oss-security/2021/10/09/1
- http://packetstormsecurity.com/files/164418/Apache-HTTP-Server-2.4.49-Path-Traversal.html
- http://packetstormsecurity.com/files/164418/Apache-HTTP-Server-2.4.49-Path-Traversal-Remote-Code-Execution.ht…
- http://www.openwall.com/lists/oss-security/2021/10/11/4
Más fallos explotados de Apache
| Añadido | Vulnerabilidad | Producto | Gravedad | Prob. de ataque |
|---|---|---|---|---|
| 1 may 2025 | Improper Escaping of Output | HTTP Server | Crítica 9,1 | >99,9% |
| 3 nov 2021 | Privilege Escalation | HTTP Server | Alto 7,8 | 65% |
| 3 nov 2021 | Path Traversal | HTTP Server | Crítica 9,8 | >99,9% |
| 8 oct 2026 | Command Injection | Struts | Alto 8,1 | 97% |
| 4 ago 2026 | Missing Encryption of Sensitive Data | Tomcat | Alto 7,5 | 99% |
| 16 abr 2026 | Improper Input Validation | ActiveMQ | Alto 8,8 | 98% |
| 1 abr 2025 | Path Equivalence | Tomcat | Crítica 10,0 | 99,9% |
| 4 feb 2025 | Forced Browsing | OFBiz | Crítica 9,8 | >99,9% |
Fuentes: Known Exploited Vulnerabilities (CISA, dominio público), CVE records (cve.org) y EPSS (FIRST). La probabilidad de ataque es la estimación EPSS de que alguien intente explotar el fallo en los próximos 30 días.