CVE-2022-3095 in Dart
Summary
by MITRE • 10/27/2022
The implementation of backslash parsing in the Dart URI class for versions prior to 2.18 and Flutter versions prior to 3.30 differs from the WhatWG URL standards. Dart uses the RFC 3986 syntax, which creates incompatibilities with the '\' characters in URIs, which can lead to auth bypass in webapps interpreting URIs. We recommend updating Dart or Flutter to mitigate the issue.
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Analysis
by VulDB Data Team • 11/26/2022
The vulnerability identified as CVE-2022-3095 stems from a fundamental discrepancy in how the Dart programming language handles backslash character parsing within URI strings. This issue specifically affects versions of Dart prior to 2.18 and Flutter prior to 3.30, creating a critical incompatibility with the widely adopted WhatWG URL standards that govern modern web URI interpretation. The core problem manifests when web applications process URIs containing backslash characters, as the Dart implementation follows RFC 3986 syntax rather than the more contemporary and universally accepted standards. This parsing inconsistency creates a dangerous scenario where authentication mechanisms can be bypassed due to the differing interpretation of URI components.
The technical flaw resides in the Dart URI class implementation where backslash characters are not properly normalized or handled according to modern web standards. When a URI containing backslashes is processed by Dart's URI parser, the system fails to correctly interpret these characters in the context of web application security. This discrepancy particularly impacts authentication systems that rely on URI parsing for access control decisions, as the backslash characters can be manipulated to alter the intended URI structure. The vulnerability creates a path for attackers to exploit the difference between Dart's RFC 3986 compliant parsing and the WhatWG URL specification that browsers and modern web applications expect. According to CWE-166, this represents a weakness in the design of URI parsing logic that directly impacts application security.
The operational impact of this vulnerability extends beyond simple parsing errors to create significant security risks in web applications built with Dart or Flutter frameworks. Authentication bypass opportunities arise when applications interpret URIs differently based on the parsing method used, potentially allowing unauthorized access to protected resources. Attackers can craft malicious URIs containing backslash characters that, when processed by vulnerable Dart applications, appear to point to different locations than intended, thereby circumventing access controls and authentication mechanisms. This vulnerability particularly affects web applications that rely on URI-based routing, session management, or access control systems where the proper interpretation of backslash characters is critical for security enforcement.
Mitigation strategies for CVE-2022-3095 require immediate updates to affected Dart and Flutter versions to align with current URI parsing standards. Organizations should prioritize upgrading to Dart 2.18 or later and Flutter 3.30 or later to ensure compliance with WhatWG URL specifications. Additionally, developers should implement comprehensive URI validation and normalization routines within their applications to detect and handle backslash characters properly before processing. Security teams should conduct thorough vulnerability assessments of all web applications using Dart or Flutter frameworks to identify potential exploitation vectors. The ATT&CK framework categorizes this issue under T1190 - Exploit Public-Facing Application, as it represents a vulnerability in application parsing logic that can be exploited remotely. Organizations should also consider implementing network monitoring to detect unusual URI patterns that might indicate exploitation attempts, particularly in applications that handle user-provided URI data.