Internet Bug Bounty · Report #2585378
important: Apache HTTP Server weakness in mod_rewrite when first segment of substitution matches filesystem path. (CVE-2024-38475)
Summary
important: Apache HTTP Server weakness in mod_rewrite when first segment of substitution matches filesystem path. (CVE-2024-38475)
Improper escaping of output in mod_rewrite in Apache HTTP Server 2.4.59 and earlier allows an attacker to map URLs to filesystem locations that are permitted to be served by the server but are not intentionally/directly reachable by any URL, resulting in code execution or source code disclosure.
Substitutions in server context that use a backreferences or variables as the first segment of the substitution are affected. Some unsafe RewiteRules will be broken by this change and the rewrite flag "UnsafePrefixStat" can be used to opt back in once ensuring the substitution is appropriately constrained.
Acknowledgements: finder: Orange Tsai (@orange_8361) from DEVCORE
Reported to security team: 2024-04-01 fixed by r1918561 in 2.4.x: 2024-07-01 Update 2.4.60 released: 2024-07-01 Affects: 2.4.0 through 2.4.59
How it was found
I reported this vulnerability through the official Apache HTTP Server security email on April 1, 2024, and received a fix along with a CVE number on July 1, 2024. You can check detailed information from there:
Impact
Improper escaping of output in mod_rewrite in Apache HTTP Server 2.4.59 and earlier allows an attacker to map URLs to filesystem locations that are permitted to be served by the server but are not intentionally/directly reachable by any URL, resulting in code execution or source code disclosure.
Substitutions in server context that use a backreferences or variables as the first segment of the substitution are affected. Some unsafe RewiteRules will be broken by this change and the rewrite flag "UnsafePrefixStat" can be used to opt back in once ensuring the substitution is appropriately constrained.