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GHSA-7mqq-6cf9-v2qp
No affected components available
Summary
Rack::Directory interpolates the configured root path directly into a regular expression when deriving the displayed directory path. If root contains regex metacharacters such as +, *, or ., the prefix stripping can fail and the generated directory listing may expose the full filesystem path in the HTML output.
Details
Rack::Directory::DirectoryBody#each computes the visible path using code equivalent to:
show_path = Utils.escape_html(path.sub(/\A#{root}/, ''))
Here, root is a developer-configured filesystem path. It is normalized earlier with File.expand_path(root) and then inserted directly into a regular expression without escaping.
Because the value is treated as regex syntax rather than as a literal string, metacharacters in the configured path can change how the prefix match behaves. When that happens, the expected root prefix is not removed from path, and the absolute filesystem path is rendered into the HTML directory listing.
Impact
If Rack::Directory is configured to serve a directory whose absolute path contains regex metacharacters, the generated directory listing may disclose the full server filesystem path instead of only the request-relative path.
This can expose internal deployment details such as directory layout, usernames, mount points, or naming conventions that would otherwise not be visible to clients.
Mitigation
- Update to a patched version of Rack in which the root prefix is removed using an escaped regular expression.
- Avoid using
Rack::Directorywith a root path that contains regular expression metacharacters.
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a low impact on the confidentiality of the information.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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