CVE-2022-3095 is a vulnerability in the Dart programming language's URI class implementation prior to version 2.18 and in Flutter versions prior to 3.30. The issue arises from the way Dart parses backslash ('\\') characters in URIs, which deviates from the WhatWG URL standards and instead follows the RFC 3986 syntax. This discrepancy causes incompatibilities in URI interpretation, particularly in web applications that rely on Dart or Flutter for URI handling. Improper input validation (CWE-20) of these backslash characters can lead to authentication bypass scenarios. Specifically, web applications that interpret URIs using Dart's implementation may incorrectly process or normalize URIs containing backslashes, potentially allowing attackers to circumvent authentication controls by manipulating URI paths or parameters. Although no known exploits have been reported in the wild, the vulnerability poses a risk to applications that depend on Dart or Flutter for URI parsing and security enforcement. The recommended mitigation is to update Dart to version 2.18 or later and Flutter to version 3.30 or later, where the URI parsing behavior aligns with the WhatWG URL standards, eliminating the backslash parsing discrepancy.

For European organizations, the impact of this vulnerability can be significant, especially for those developing or deploying web applications using Dart or Flutter frameworks. Authentication bypass can lead to unauthorized access to sensitive data, user accounts, or administrative functions, undermining confidentiality and integrity. This can result in data breaches, regulatory non-compliance (e.g., GDPR violations), and reputational damage. The vulnerability affects the availability of secure authentication mechanisms, potentially allowing attackers to escalate privileges or access restricted resources. Organizations in sectors such as finance, healthcare, government, and critical infrastructure that rely on Dart/Flutter for web or mobile app development are particularly at risk. Given the widespread adoption of Flutter for cross-platform development, the scope of affected systems is broad, increasing the potential attack surface. However, the absence of known exploits and the medium severity rating suggest that while the risk is real, it may require targeted conditions to be exploited effectively.

1. Immediate upgrade of Dart to version 2.18 or later and Flutter to version 3.30 or later to ensure URI parsing conforms to WhatWG standards and eliminates the backslash parsing issue. 2. Conduct a thorough code review of all URI handling logic in web applications to identify and remediate any custom parsing or normalization that might be vulnerable to backslash manipulation. 3. Implement strict input validation and sanitization on all URI inputs at the application layer, ensuring that backslash characters are either properly escaped or rejected where not expected. 4. Employ runtime application self-protection (RASP) or web application firewall (WAF) rules that detect and block suspicious URI patterns involving backslashes or unusual encoding. 5. Perform security testing, including fuzzing and penetration testing focused on URI parsing and authentication flows, to detect potential bypass scenarios. 6. Monitor application logs for anomalous URI access patterns that could indicate exploitation attempts. 7. Educate developers on the importance of adhering to URI standards and the risks of improper input validation in URI processing.