CVE-2025-27610

Summary

Rack::Static can serve files under the specified root: even if urls: are provided, which may expose other files under the specified root: unexpectedly.

Details

The vulnerability occurs because Rack::Static does not properly sanitize user-supplied paths before serving files. Specifically, encoded path traversal sequences are not correctly validated, allowing attackers to access files outside the designated static file directory.

Impact

By exploiting this vulnerability, an attacker can gain access to all files under the specified root: directory, provided they are able to determine then path of the file.

Mitigation

• Update to the latest version of Rack, or
• Remove usage of Rack::Static, or
• Ensure that root: points at a directory path which only contains files which should be accessed publicly.

It is likely that a CDN or similar static file server would also mitigate the issue.

Rack provides a minimal, modular and adaptable interface for developing web applications in Ruby. By wrapping HTTP requests and responses in the simplest way possible, it unifies and distills the API for web servers, web frameworks, and software in between (the so-called middleware) into a single method call.

Security Fix(es):

Rack provides an interface for developing web applications in Ruby. Prior to versions 2.2.11, 3.0.12, and 3.1.10, Rack::CommonLogger can be exploited by crafting input that includes newline characters to manipulate log entries. The supplied proof-of-concept demonstrates injecting malicious content into logs. When a user provides the authorization credentials via Rack::Auth::Basic, if success, the username will be put in env['REMOTE_USER'] and later be used by Rack::CommonLogger for logging purposes. The issue occurs when a server intentionally or unintentionally allows a user creation with the username contain CRLF and white space characters, or the server just want to log every login attempts. If an attacker enters a username with CRLF character, the logger will log the malicious username with CRLF characters into the logfile. Attackers can break log formats or insert fraudulent entries, potentially obscuring real activity or injecting malicious data into log files. Versions 2.2.11, 3.0.12, and 3.1.10 contain a fix.(CVE-2025-25184)

Rack is a modular Ruby web server interface. The Rack::Sendfile middleware logs unsanitised header values from the X-Sendfile-Type header. An attacker can exploit this by injecting escape sequences (such as newline characters) into the header, resulting in log injection. This vulnerability is fixed in 2.2.12, 3.0.13, and 3.1.11.(CVE-2025-27111)

Rack provides an interface for developing web applications in Ruby. Prior to versions 2.2.13, 3.0.14, and 3.1.12, Rack::Static can serve files under the specified root: even if urls: are provided, which may expose other files under the specified root: unexpectedly. The vulnerability occurs because Rack::Static does not properly sanitize user-supplied paths before serving files. Specifically, encoded path traversal sequences are not correctly validated, allowing attackers to access files outside the designated static file directory. By exploiting this vulnerability, an attacker can gain access to all files under the specified root: directory, provided they are able to determine then path of the file. Versions 2.2.13, 3.0.14, and 3.1.12 contain a patch for the issue. Other mitigations include removing usage of Rack::Static, or ensuring that root: points at a directory path which only contains files which should be accessed publicly. It is likely that a CDN or similar static file server would also mitigate the issue.(CVE-2025-27610)

Rack provides an interface for developing web applications in Ruby. Prior to versions 2.2.13, 3.0.14, and 3.1.12, Rack::Static can serve files under the specified root: even if urls: are provided, which may expose other files under the specified root: unexpectedly. The vulnerability occurs because Rack::Static does not properly sanitize user-supplied paths before serving files. Specifically, encoded path traversal sequences are not correctly validated, allowing attackers to access files outside the designated static file directory. By exploiting this vulnerability, an attacker can gain access to all files under the specified root: directory, provided they are able to determine then path of the file. Versions 2.2.13, 3.0.14, and 3.1.12 contain a patch for the issue. Other mitigations include removing usage of Rack::Static, or ensuring that root: points at a directory path which only contains files which should be accessed publicly. It is likely that a CDN or similar static file server would also mitigate the issue.

Possible Log Injection in Rack::CommonLogger. (CVE-2025-25184) Escape Sequence Injection vulnerability in Rack lead to Possible Log Injection. (CVE-2025-27111) Local File Inclusion in Rack::Static. (CVE-2025-27610)

These are all security issues fixed in the ruby3.4-rubygem-rack-2.2-2.2.13-1.1 package on the GA media of openSUSE Tumbleweed.

These are all security issues fixed in the ruby4.0-rubygem-rack-2.2-2.2.22-1.1 package on the GA media of openSUSE Tumbleweed.

This update for rubygem-rack-1_6 fixes the following issues:

• CVE-2025-27610: Fixed improper sanitization of user-supplied paths when serving files leading to local file inclusion (bsc#1239298).
• CVE-2025-25184: Fixed Rack::CommonLogger log entry manipulation (bsc#1237141).

This update for rubygem-rack fixes the following issues:

• CVE-2025-25184: Fixed escape sequence injection vulnerability in rack leading to possible log injection (bsc#1237141)
• CVE-2025-27111: Fixed escape sequence injection vulnerability in rack leading to possible log injection (bsc#1238607)
• CVE-2025-27610: Fixed improper sanitization of user-supplied paths (bsc#1239298)

Nhật Thái Đỗ discovered that Rack incorrectly handled certain usernames. A remote attacker could possibly use this issue to perform CRLF injection. (CVE-2025-25184)

Phạm Quang Minh discovered that Rack incorrectly handled certain headers. A remote attacker could possibly use this issue to perform log injection. (CVE-2025-27111)

Phạm Quang Minh discovered that Rack did not properly handle relative file paths. A remote attacker could potentially exploit this to include local files that should have been inaccessible. (CVE-2025-27610)

USN-7366-1 fixed vulnerabilities in Rack. This update provides the corresponding updates for Ubuntu 25.04.

Original advisory details:

Nhật Thái Đỗ discovered that Rack incorrectly handled certain usernames. A remote attacker could possibly use this issue to perform CRLF injection. (CVE-2025-25184)

Phạm Quang Minh discovered that Rack incorrectly handled certain headers. A remote attacker could possibly use this issue to perform log injection. (CVE-2025-27111)

Phạm Quang Minh discovered that Rack did not properly handle relative file paths. A remote attacker could potentially exploit this to include local files that should have been inaccessible. (CVE-2025-27610)