CVE-2021-42574

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.
Code Injection
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
8.3 HIGH
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: 96%
Affected Products (NVD)
VendorProductVersion
unicodeunicode
𝑥
< 14.0.0
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
rustc
bookworm
1.63.0+dfsg1-2
fixed
bullseye
unimportant
sid
1.82.0+dfsg1-2
fixed
trixie
1.82.0+dfsg1-2
fixed
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
rustc
bionic
not-affected
focal
Fixed 1.57.0+dfsg1+llvm-0ubuntu1~20.04.1
released
hirsute
ignored
impish
ignored
jammy
Fixed 1.57.0+dfsg1+llvm-0ubuntu2
released
kinetic
ignored
lunar
not-affected
mantic
not-affected
noble
not-affected
trusty
not-affected
xenial
not-affected
Red Hat logo
Red Hat Enterprise Linux Releases
Red Hat Product
Release
annobin
RHEL 8
0:9.72-1.el8_5.2
fixed
RHEL 8.4 AUS
0:9.50-1.el8_4.1
fixed
RHEL 8.4 E4S
0:9.50-1.el8_4.1
fixed
RHEL 8.4 EUS
0:9.50-1.el8_4.1
fixed
RHEL 8.4 TUS
0:9.50-1.el8_4.1
fixed
annobin-annocheck
RHEL 8
0:9.72-1.el8_5.2
fixed
RHEL 8.4 AUS
0:9.50-1.el8_4.1
fixed
RHEL 8.4 E4S
0:9.50-1.el8_4.1
fixed
RHEL 8.4 EUS
0:9.50-1.el8_4.1
fixed
RHEL 8.4 TUS
0:9.50-1.el8_4.1
fixed
binutils
RHEL 7
0:2.27-44.base.el7_9.1
fixed
RHEL 8
0:2.30-108.el8_5.1
fixed
RHEL 8.1 E4S
0:2.30-58.el8_1.3
fixed
RHEL 8.1 EUS
0:2.30-58.el8_1.3
fixed
RHEL 8.2 AUS
0:2.30-73.el8_2.1
fixed
RHEL 8.2 E4S
0:2.30-73.el8_2.1
fixed
RHEL 8.2 EUS
0:2.30-73.el8_2.1
fixed
RHEL 8.2 TUS
0:2.30-73.el8_2.1
fixed
RHEL 8.4 AUS
0:2.30-93.el8_4.2
fixed
RHEL 8.4 E4S
0:2.30-93.el8_4.2
fixed
RHEL 8.4 EUS
0:2.30-93.el8_4.2
fixed
RHEL 8.4 TUS
0:2.30-93.el8_4.2
fixed
binutils-devel
RHEL 7
0:2.27-44.base.el7_9.1
fixed
RHEL 8
0:2.30-108.el8_5.1
fixed
RHEL 8.1 E4S
0:2.30-58.el8_1.3
fixed
RHEL 8.1 EUS
0:2.30-58.el8_1.3
fixed
RHEL 8.2 AUS
0:2.30-73.el8_2.1
fixed
RHEL 8.2 E4S
0:2.30-73.el8_2.1
fixed
RHEL 8.2 EUS
0:2.30-73.el8_2.1
fixed
RHEL 8.2 TUS
0:2.30-73.el8_2.1
fixed
RHEL 8.4 AUS
0:2.30-93.el8_4.2
fixed
RHEL 8.4 E4S
0:2.30-93.el8_4.2
fixed
RHEL 8.4 EUS
0:2.30-93.el8_4.2
fixed
RHEL 8.4 TUS
0:2.30-93.el8_4.2
fixed
cpp
RHEL 8
0:8.5.0-4.el8_5
fixed
gcc
RHEL 8
0:8.5.0-4.el8_5
fixed
gcc-c
RHEL 8
0:8.5.0-4.el8_5
fixed
gcc-gdb-plugin
RHEL 8
0:8.5.0-4.el8_5
fixed
gcc-gfortran
RHEL 8
0:8.5.0-4.el8_5
fixed
gcc-offload-nvptx
RHEL 8
0:8.5.0-4.el8_5
fixed
gcc-plugin-devel
RHEL 8
0:8.5.0-4.el8_5
fixed
gcc-toolset-10-binutils
RHEL 8
0:2.35-8.el8_5.6
fixed
RHEL 8.4 AUS
0:2.35-8.el8_4.5
fixed
RHEL 8.4 E4S
0:2.35-8.el8_4.5
fixed
RHEL 8.4 EUS
0:2.35-8.el8_4.5
fixed
RHEL 8.4 TUS
0:2.35-8.el8_4.5
fixed
gcc-toolset-10-binutils-devel
RHEL 8
0:2.35-8.el8_5.6
fixed
RHEL 8.4 AUS
0:2.35-8.el8_4.5
fixed
RHEL 8.4 E4S
0:2.35-8.el8_4.5
fixed
RHEL 8.4 EUS
0:2.35-8.el8_4.5
fixed
RHEL 8.4 TUS
0:2.35-8.el8_4.5
fixed
gcc-toolset-10-gcc
RHEL 8
0:10.3.1-1.2.el8_5
fixed
gcc-toolset-10-gcc-c
RHEL 8
0:10.3.1-1.2.el8_5
fixed
gcc-toolset-10-gcc-gdb-plugin
RHEL 8
0:10.3.1-1.2.el8_5
fixed
gcc-toolset-10-gcc-gfortran
RHEL 8
0:10.3.1-1.2.el8_5
fixed
gcc-toolset-10-gcc-plugin-devel
RHEL 8
0:10.3.1-1.2.el8_5
fixed
gcc-toolset-10-libasan-devel
RHEL 8
0:10.3.1-1.2.el8_5
fixed
gcc-toolset-10-libatomic-devel
RHEL 8
0:10.3.1-1.2.el8_5
fixed
gcc-toolset-10-libitm-devel
RHEL 8
0:10.3.1-1.2.el8_5
fixed
gcc-toolset-10-liblsan-devel
RHEL 8
0:10.3.1-1.2.el8_5
fixed
gcc-toolset-10-libquadmath-devel
RHEL 8
0:10.3.1-1.2.el8_5
fixed
gcc-toolset-10-libstdc
RHEL 8
0:10.3.1-1.2.el8_5
fixed
gcc-toolset-10-libtsan-devel
RHEL 8
0:10.3.1-1.2.el8_5
fixed
gcc-toolset-10-libubsan-devel
RHEL 8
0:10.3.1-1.2.el8_5
fixed
gcc-toolset-11-annobin-annocheck
RHEL 8
0:9.85-1.el8_5.1
fixed
gcc-toolset-11-annobin-docs
RHEL 8
0:9.85-1.el8_5.1
fixed
gcc-toolset-11-annobin-plugin-gcc
RHEL 8
0:9.85-1.el8_5.1
fixed
gcc-toolset-11-binutils
RHEL 8
0:2.36.1-1.el8_5.1
fixed
gcc-toolset-11-binutils-devel
RHEL 8
0:2.36.1-1.el8_5.1
fixed
gcc-toolset-11-gcc
RHEL 8
0:11.2.1-1.2.el8_5
fixed
gcc-toolset-11-gcc-c
RHEL 8
0:11.2.1-1.2.el8_5
fixed
gcc-toolset-11-gcc-gdb-plugin
RHEL 8
0:11.2.1-1.2.el8_5
fixed
gcc-toolset-11-gcc-gfortran
RHEL 8
0:11.2.1-1.2.el8_5
fixed
gcc-toolset-11-gcc-plugin-devel
RHEL 8
0:11.2.1-1.2.el8_5
fixed
gcc-toolset-11-libasan-devel
RHEL 8
0:11.2.1-1.2.el8_5
fixed
gcc-toolset-11-libatomic-devel
RHEL 8
0:11.2.1-1.2.el8_5
fixed
gcc-toolset-11-libgccjit
RHEL 8
0:11.2.1-1.2.el8_5
fixed
gcc-toolset-11-libgccjit-devel
RHEL 8
0:11.2.1-1.2.el8_5
fixed
gcc-toolset-11-libgccjit-docs
RHEL 8
0:11.2.1-1.2.el8_5
fixed
gcc-toolset-11-libitm-devel
RHEL 8
0:11.2.1-1.2.el8_5
fixed
gcc-toolset-11-liblsan-devel
RHEL 8
0:11.2.1-1.2.el8_5
fixed
gcc-toolset-11-libquadmath-devel
RHEL 8
0:11.2.1-1.2.el8_5
fixed
gcc-toolset-11-libstdc
RHEL 8
0:11.2.1-1.2.el8_5
fixed
gcc-toolset-11-libtsan-devel
RHEL 8
0:11.2.1-1.2.el8_5
fixed
gcc-toolset-11-libubsan-devel
RHEL 8
0:11.2.1-1.2.el8_5
fixed
libasan
RHEL 8
0:8.5.0-4.el8_5
fixed
libasan6
RHEL 8
0:11.2.1-1.2.el8_5
fixed
libatomic
RHEL 8
0:8.5.0-4.el8_5
fixed
libatomic-static
RHEL 8
0:8.5.0-4.el8_5
fixed
libgcc
RHEL 8
0:8.5.0-4.el8_5
fixed
libgfortran
RHEL 8
0:8.5.0-4.el8_5
fixed
libgomp
RHEL 8
0:8.5.0-4.el8_5
fixed
libgomp-offload-nvptx
RHEL 8
0:8.5.0-4.el8_5
fixed
libitm
RHEL 8
0:8.5.0-4.el8_5
fixed
libitm-devel
RHEL 8
0:8.5.0-4.el8_5
fixed
liblsan
RHEL 8
0:8.5.0-4.el8_5
fixed
libquadmath
RHEL 8
0:8.5.0-4.el8_5
fixed
libquadmath-devel
RHEL 8
0:8.5.0-4.el8_5
fixed
libstdc
RHEL 8
0:8.5.0-4.el8_5
fixed
libtsan
RHEL 8
0:8.5.0-4.el8_5
fixed
libubsan
RHEL 8
0:8.5.0-4.el8_5
fixed
References