GLib D-Bus Cookie Context Path Traversal

Executive Summary

CVE-2026-58015 is a path traversal vulnerability in the GLib D-Bus client-side implementation of the DBUS_COOKIE_SHA1 SASL authentication mechanism.

The flaw occurs because the client does not validate the cookie_context parameter received from the server, which can contain path traversal sequences like ../. This parameter is used to build a filesystem path, allowing a malicious D-Bus server to cause the client to read arbitrary files outside the intended directory.

The client then uses part of the file's contents in a SHA1 hash computation and sends the result back to the server, enabling the server to verify guessed file contents and exfiltrate sensitive data.

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Impact Analysis

This vulnerability can lead to unauthorized reading of arbitrary files on the client system by a malicious D-Bus server.

Sensitive data stored in files outside the intended directory can be exfiltrated without user knowledge, potentially exposing confidential information.

Since the vulnerability allows data exfiltration through the authentication mechanism, it can compromise the confidentiality of the affected system.

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Detection Guidance

This vulnerability involves the GLib D-Bus client accepting a malicious cookie_context parameter containing path traversal sequences from a D-Bus server. Detection would involve monitoring D-Bus client authentication attempts for unusual or suspicious cookie_context values that contain characters such as ../ or other path traversal sequences.

Since the vulnerability exploits the DBUS_COOKIE_SHA1 SASL authentication mechanism, you can inspect D-Bus traffic or logs for authentication exchanges involving this mechanism and look for cookie_context parameters with suspicious path traversal patterns.

Specific commands are not provided in the resources, but general approaches include:

• Using tools like tcpdump or Wireshark to capture and analyze D-Bus traffic for suspicious authentication parameters.
• Checking system logs for D-Bus authentication errors or unusual activity.
• Using grep or similar tools to search for suspicious cookie_context values in D-Bus related logs or debug output.

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Mitigation Strategies

Immediate mitigation steps include preventing the GLib D-Bus client from accepting malicious cookie_context parameters containing path traversal sequences.

Since the vulnerability arises from lack of validation of the cookie_context parameter, applying patches or updates provided by your OS or GLib maintainers that fix this validation issue is the most effective step.

In the absence of patches, consider restricting or monitoring D-Bus server connections to trusted sources only, to reduce exposure to malicious servers.

Additionally, auditing and limiting file permissions in the ~/.dbus-keyrings/ directory may reduce the impact of potential exploitation.

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Compliance Impact

This vulnerability allows a malicious D-Bus server to cause the client to read arbitrary files and exfiltrate sensitive data by exploiting a path traversal flaw in the GLib D-Bus client-side implementation. Such unauthorized access and potential leakage of sensitive information could lead to non-compliance with data protection regulations like GDPR and HIPAA, which require strict controls over the confidentiality and integrity of personal and sensitive data.

Specifically, the exfiltration of sensitive data through this vulnerability may violate requirements for data confidentiality and breach notification obligations under these standards.

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