CVE-2021-41773
Apache HTTP Server Path Traversal Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 17 November 2021). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
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.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 99.99% probability · 100th percentile
- CISA KEV
- Listed 3 November 2021 · due 17 November 2021 · used in ransomware campaigns
- Weakness
- CWE-22
- Affected
- apache/http server · fedoraproject/fedora · oracle/instantis enterprisetrack · netapp/cloud backup
- Source
- security@apache.org
CISA notes
Apply updates per vendor instructions. https://nvd.nist.gov/vuln/detail/CVE-2021-41773
References
- http://packetstormsecurity.com/files/164418/Apache-HTTP-Server-2.4.49-Path-Traversal-Remote-Code-Execution.htmlExploit, Third Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/164418/Apache-HTTP-Server-2.4.49-Path-Traversal.htmlExploit, Third Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/164629/Apache-2.4.49-2.4.50-Traversal-Remote-Code-Execution.htmlExploit, Third Party Advisory, VDB Entry
- http://packetstormsecurity.com/files/164941/Apache-HTTP-Server-2.4.50-Remote-Code-Execution.htmlExploit, Third Party Advisory, VDB Entry
- http://www.openwall.com/lists/oss-security/2021/10/05/2Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/10/07/1Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/10/07/6Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/10/08/1Exploit, Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/10/08/2Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/10/08/3Exploit, Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/10/08/4Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/10/08/5Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/10/08/6Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/10/09/1Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/10/11/4Mailing List, Patch, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/10/15/3Mailing List, Patch, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/10/16/1Mailing List, Third Party Advisory
- https://httpd.apache.org/security/vulnerabilities_24.htmlRelease Notes, Vendor Advisory
- https://lists.apache.org/thread.html/r17a4c6ce9aff662efd9459e9d1850ab4a611cb23392fc68264c72cb3%40%3Ccvs.httpd.apache.org%3EMailing List, Patch
- https://lists.apache.org/thread.html/r6abf5f2ba6f1aa8b1030f95367aaf17660c4e4c78cb2338aee18982f%40%3Cusers.httpd.apache.org%3EMailing List
- https://lists.apache.org/thread.html/r7c795cd45a3384d4d27e57618a215b0ed19cb6ca8eb070061ad5d837%40%3Cannounce.apache.org%3EMailing List
- https://lists.apache.org/thread.html/r98d704ed4377ed889d40479db79ed1ee2f43b2ebdd79ce84b042df45%40%3Cannounce.apache.org%3EMailing List
- https://lists.apache.org/thread.html/rb5b0e46f179f60b0c70204656bc52fcb558e961cb4d06a971e9e3efb%40%3Cusers.httpd.apache.org%3EMailing List
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RMIIEFINL6FUIOPD2A3M5XC6DH45Y3CC/Release Notes
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WS5RVHOIIRECG65ZBTZY7IEJVWQSQPG3/Release Notes
- https://security.gentoo.org/glsa/202208-20Third Party Advisory
- https://security.netapp.com/advisory/ntap-20211029-0009/Third Party Advisory
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-httpd-pathtrv-LAzg68cZThird Party Advisory
- https://www.oracle.com/security-alerts/cpujan2022.htmlPatch, Third Party Advisory
- http://packetstormsecurity.com/files/164418/Apache-HTTP-Server-2.4.49-Path-Traversal-Remote-Code-Execution.htmlExploit, Third Party Advisory, VDB Entry
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.