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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2021-42574 Detail

Disputed     

Current Description

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.


View Analysis Description

Metrics

 
NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

References to Advisories, Solutions, and Tools

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Hyperlink Resource
http://www.openwall.com/lists/oss-security/2021/11/01/1 Exploit  Mailing List  Mitigation  Third Party Advisory 
http://www.openwall.com/lists/oss-security/2021/11/01/1 Exploit  Mailing List  Mitigation  Third Party Advisory 
http://www.openwall.com/lists/oss-security/2021/11/01/4 Exploit  Mailing List  Third Party Advisory 
http://www.openwall.com/lists/oss-security/2021/11/01/4 Exploit  Mailing List  Third Party Advisory 
http://www.openwall.com/lists/oss-security/2021/11/01/5 Mailing List  Third Party Advisory 
http://www.openwall.com/lists/oss-security/2021/11/01/5 Mailing List  Third Party Advisory 
http://www.openwall.com/lists/oss-security/2021/11/01/6 Mailing List  Third Party Advisory 
http://www.openwall.com/lists/oss-security/2021/11/01/6 Mailing List  Third Party Advisory 
http://www.openwall.com/lists/oss-security/2021/11/02/10 Mailing List 
http://www.openwall.com/lists/oss-security/2021/11/02/10 Mailing List 
http://www.unicode.org/versions/Unicode14.0.0/ Release Notes  Vendor Advisory 
http://www.unicode.org/versions/Unicode14.0.0/ Release Notes  Vendor Advisory 
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IH2RG5YTR6ZZOLUV3EUPZEIJR7XHJLVD/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IH2RG5YTR6ZZOLUV3EUPZEIJR7XHJLVD/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LQNTFF24ROHLVPLUOEISBN3F7QM27L4U/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LQNTFF24ROHLVPLUOEISBN3F7QM27L4U/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QUPA37D57VPTDLSXOOGF4UXUEADOC4PQ/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QUPA37D57VPTDLSXOOGF4UXUEADOC4PQ/
https://security.gentoo.org/glsa/202210-09 Third Party Advisory 
https://security.gentoo.org/glsa/202210-09 Third Party Advisory 
https://trojansource.codes Exploit  Technical Description  Third Party Advisory 
https://trojansource.codes Exploit  Technical Description  Third Party Advisory 
https://www.kb.cert.org/vuls/id/999008 Third Party Advisory  US Government Resource 
https://www.kb.cert.org/vuls/id/999008 Third Party Advisory  US Government Resource 
https://www.scyon.nl/post/trojans-in-your-source-code Exploit  Mitigation  Third Party Advisory 
https://www.scyon.nl/post/trojans-in-your-source-code Exploit  Mitigation  Third Party Advisory 
https://www.starwindsoftware.com/security/sw-20220804-0002/ Third Party Advisory 
https://www.starwindsoftware.com/security/sw-20220804-0002/ Third Party Advisory 
https://www.unicode.org/reports/tr31/ Technical Description  Vendor Advisory 
https://www.unicode.org/reports/tr31/ Technical Description  Vendor Advisory 
https://www.unicode.org/reports/tr36/ Technical Description  Vendor Advisory 
https://www.unicode.org/reports/tr36/ Technical Description  Vendor Advisory 
https://www.unicode.org/reports/tr39/ Technical Description  Vendor Advisory 
https://www.unicode.org/reports/tr39/ Technical Description  Vendor Advisory 
https://www.unicode.org/reports/tr9/tr9-44.html#HL4 Technical Description  Vendor Advisory 
https://www.unicode.org/reports/tr9/tr9-44.html#HL4 Technical Description  Vendor Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-94 Improper Control of Generation of Code ('Code Injection') cwe source acceptance level NIST  

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Change History

25 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2021-42574
NVD Published Date:
11/01/2021
NVD Last Modified:
11/21/2024
Source:
MITRE