high
8.3
CWE
94
Advisory Published
Updated

CVE-2021-42574: Code Injection

First published: Mon Nov 01 2021(Updated: )

** DISPUTED ** An issue was discovered in the Bidirectional Algorithm in the Unicode Specification through 14.0. It permits the visual reordering of characters via control sequences, which can be used to craft source code that renders different logic than the logical ordering of tokens ingested by compilers and interpreters. Adversaries can leverage this to encode source code for compilers accepting Unicode such that targeted vulnerabilities are introduced invisibly to human reviewers. NOTE: the Unicode Consortium offers the following alternative approach to presenting this concern. An issue is noted in the nature of international text that can affect applications that implement support for The Unicode Standard and the Unicode Bidirectional Algorithm (all versions). Due to text display behavior when text includes left-to-right and right-to-left characters, the visual order of tokens may be different from their logical order. Additionally, control characters needed to fully support the requirements of bidirectional text can further obfuscate the logical order of tokens. Unless mitigated, an adversary could craft source code such that the ordering of tokens perceived by human reviewers does not match what will be processed by a compiler/interpreter/etc. The Unicode Consortium has documented this class of vulnerability in its document, Unicode Technical Report #36, Unicode Security Considerations. The Unicode Consortium also provides guidance on mitigations for this class of issues in Unicode Technical Standard #39, Unicode Security Mechanisms, and in Unicode Standard Annex #31, Unicode Identifier and Pattern Syntax. Also, the BIDI specification allows applications to tailor the implementation in ways that can mitigate misleading visual reordering in program text; see HL4 in Unicode Standard Annex #9, Unicode Bidirectional Algorithm.

Credit: cve@mitre.org cve@mitre.org

Affected SoftwareAffected VersionHow to fix
Unicode Unicode<14.0.0
Fedoraproject Fedora=33
Fedoraproject Fedora=34
Fedoraproject Fedora=35
Starwindsoftware Starwind Virtual San=v8r13-14398

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Reference Links

Frequently Asked Questions

  • What is the vulnerability ID for this issue?

    The vulnerability ID for this issue is CVE-2021-42574.

  • What is the severity of CVE-2021-42574?

    The severity of CVE-2021-42574 is high, with a severity value of 8.3.

  • What is the affected software for CVE-2021-42574?

    The affected software for CVE-2021-42574 includes Unicode (versions up to 14.0.0), Fedora (versions 33, 34, and 35), and StarWind Virtual SAN (version v8r13-14398).

  • What is the CWE ID for CVE-2021-42574?

    The CWE ID for CVE-2021-42574 is CWE-94.

  • Are there any references or additional information about CVE-2021-42574?

    Yes, there are references available for CVE-2021-42574. You can find them at the following links: [Link 1](http://www.openwall.com/lists/oss-security/2021/11/01/1), [Link 2](http://www.openwall.com/lists/oss-security/2021/11/01/4), [Link 3](http://www.openwall.com/lists/oss-security/2021/11/01/5).

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