CVE-2010-0385 in Tor
Summary
by MITRE
Tor before 0.2.1.22, and 0.2.2.x before 0.2.2.7-alpha, when functioning as a bridge directory authority, allows remote attackers to obtain sensitive information about bridge identities and bridge descriptors via a dbg-stability.txt directory query.
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Analysis
by VulDB Data Team • 04/29/2026
The vulnerability identified as CVE-2010-0385 affects the Tor anonymity network software, specifically versions prior to 0.2.1.22 and 0.2.2.7-alpha when operating as bridge directory authorities. This flaw represents a significant security weakness in the network's infrastructure components that are responsible for maintaining and distributing information about Tor bridges. Tor bridges serve as critical entry points for users who cannot access the regular Tor network due to censorship or blocking, making their protection essential for maintaining user anonymity and network integrity.
The technical flaw stems from improper access control mechanisms within the directory authority implementation. When remote attackers submit specially crafted directory queries for dbg-stability.txt files, they can bypass normal authorization checks that should restrict access to sensitive bridge identity information and bridge descriptors. This vulnerability allows attackers to gather detailed information about bridge configurations, operational characteristics, and potentially even the identities of bridge operators. The issue manifests specifically in the bridge directory authority functionality where the system fails to properly validate query requests and enforce appropriate access controls for debugging and stability information.
The operational impact of this vulnerability is severe for the Tor network's security model and user privacy. Attackers who exploit this weakness can obtain sensitive data about bridge operations that could compromise the anonymity of Tor users who rely on bridges for access. The leaked information about bridge identities and descriptors could enable sophisticated adversaries to identify and target specific bridge operators, potentially leading to their exposure and the subsequent degradation of anonymity for users who depend on these bridges. This vulnerability undermines the fundamental security assumptions of the Tor network's distributed architecture and creates opportunities for targeted attacks against bridge infrastructure.
This vulnerability maps to CWE-284 Access Control Issues within the Common Weakness Enumeration taxonomy, specifically representing improper access control in directory authority services. The attack pattern aligns with ATT&CK technique T1566.002 Credential Access: Phishing for Information, as it involves obtaining sensitive information through network-based queries that should be restricted. The flaw demonstrates a critical failure in the principle of least privilege where debugging information should not be accessible to unauthenticated remote attackers. Organizations and developers should implement proper access control mechanisms and regularly audit directory authority configurations to prevent similar vulnerabilities.
The recommended mitigations include immediate upgrading to Tor versions 0.2.1.22 or 0.2.2.7-alpha which contain the necessary patches to address this access control flaw. Network administrators should also implement additional monitoring of directory query patterns to detect anomalous access attempts that might indicate exploitation attempts. Configuration hardening measures should include disabling unnecessary debugging endpoints and implementing stricter access controls for directory authority services. The vulnerability highlights the importance of maintaining up-to-date security patches and conducting regular security assessments of critical infrastructure components that handle sensitive operational data.