Input validation error in Unicode - CVE-2021-42574
Published: November 2, 2021 / Updated: September 18, 2023
Vulnerability identifier: #VU57848
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/U:Clear
CVE-ID: CVE-2021-42574
CWE-ID: CWE-20
Exploitation vector: Local access
Exploit availability:
Public exploit is available
Vendor: Unicode inc.
Affected software:
Unicode
Unicode
Detailed vulnerability description
The vulnerability allows an attacker to bypass certain security checks.
The vulnerability exists in the Bidirectional Algorithm in the Unicode Specification. 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.
An attacker can leverage this behavior to encode source code for compilers accepting Unicode such that targeted vulnerabilities are introduced invisibly to human reviewers.
How to mitigate CVE-2021-42574
Cybersecurity Help is currently unaware of any official solution to address this vulnerability.
Sources
- http://www.openwall.com/lists/oss-security/2021/11/01/1
- http://www.openwall.com/lists/oss-security/2021/11/01/4
- http://www.openwall.com/lists/oss-security/2021/11/01/5
- http://www.openwall.com/lists/oss-security/2021/11/01/6
- https://github.blog/changelog/2021-10-31-warning-about-bidirectional-unicode-text/