01 Record

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

UnratedPUBLISHEDCNA: mitre

CNA base scoreUnratedNo CNA CVSS vector

View raw JSON

02 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

03 Exploitation and scoring

Exploitation

Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.

SSVC decision

ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

12.88% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 95.9% of scored records. A rank, not a probability.

NVD base score

8.3 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H

NVD analysis status

Modified. NVD last modified this record on 2026-06-17.

Red Hat severity

Moderate. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published

2021-11-01 00:00Z4 YR AGO

Last updated

2024-08-04 03:38Z2 YR AGO

Reserved

2021-10-18

Assigning CNA

mitre

Record state

PUBLISHED

Severity

Not rated by the issuing CNA

CNA CVSS vector

Not published by the issuing CNA

Weaknesses

CWE-94Improper Control of Generation of Code ('Code Injection')Base
CWE-838Inappropriate Encoding for Output ContextBase

Data version

5.1

Document digest

6282b0cb3b4c95f48ac701496b1db54255cdca07a8bb1e7a0c78a1ad2e07697a

05 Affected products

VendorProductVersionsPlatforms

fedoraprojectfedoraNot specified—

redhatdevtoolsNot specified—

redhatenterprise_linuxNot specified—

redhatrhel_ausNot specified—

redhatrhel_e4sNot specified—

redhatrhel_eusNot specified—

redhatrhel_software_collectionsNot specified—

redhatrhel_tusNot specified—

starwindsoftwarestarwind_virtual_sanNot specified—

unicodeunicodeNot specified—

06 References

www.unicode.orghttp://www.unicode.org/versions/Unicode14.0.0/
trojansource.codeshttps://trojansource.codes
www.openwall.com[oss-security] 20211101 CVE-2021-42574: rustc 1.56.0 and bidirectional-override codepoints in source codehttp://www.openwall.com/lists/oss-security/2021/11/01/1mailing-list
www.openwall.com[oss-security] 20211101 Re: CVE-2021-42574: rustc 1.56.0 and bidirectional-override codepoints in source codehttp://www.openwall.com/lists/oss-security/2021/11/01/4mailing-list
www.openwall.com[oss-security] 20211101 Trojan Source Attackshttp://www.openwall.com/lists/oss-security/2021/11/01/6mailing-list
www.openwall.com[oss-security] 20211102 Re: CVE-2021-42574: rustc 1.56.0 and bidirectional-override codepoints in source codehttp://www.openwall.com/lists/oss-security/2021/11/01/5mailing-list
www.openwall.com[oss-security] 20211102 Re: Trojan Source Attackshttp://www.openwall.com/lists/oss-security/2021/11/02/10mailing-list
lists.fedoraproject.orgFEDORA-2021-0578e23912https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QUPA37D57VPTDLSXOOGF4UXUEADOC4PQ/vendor-advisory
lists.fedoraproject.orgFEDORA-2021-7ad3a01f6ahttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LQNTFF24ROHLVPLUOEISBN3F7QM27L4U/vendor-advisory
www.kb.cert.orgVU#999008https://www.kb.cert.org/vuls/id/999008third-party-advisory
lists.fedoraproject.orgFEDORA-2021-443139f67chttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IH2RG5YTR6ZZOLUV3EUPZEIJR7XHJLVD/vendor-advisory
www.scyon.nlhttps://www.scyon.nl/post/trojans-in-your-source-code
www.unicode.orghttps://www.unicode.org/reports/tr36/
www.unicode.orghttps://www.unicode.org/reports/tr39/
www.unicode.orghttps://www.unicode.org/reports/tr31/
www.unicode.orghttps://www.unicode.org/reports/tr9/tr9-44.html#HL4
www.starwindsoftware.comhttps://www.starwindsoftware.com/security/sw-20220804-0002/
security.gentoo.orgGLSA-202210-09https://security.gentoo.org/glsa/202210-09vendor-advisory

07 Fixed in

AlmaLinux 8

annobin
Fixed in 9.72-1.el8_5.2
annobin-annocheck
Fixed in 9.72-1.el8_5.2
binutils-devel
Fixed in 2.30-108.el8_5.1
cargo
Fixed in 1.54.0-3.module_el8.5.0+2599+d655d86c
cargo-doc
Fixed in 1.54.0-3.module_el8.5.0+2599+d655d86c
clang
Fixed in 12.0.1-4.module_el8.4.0+2600+cefb5d4c
clang-analyzer
Fixed in 12.0.1-4.module_el8.4.0+2600+cefb5d4c
clang-devel
Fixed in 12.0.1-4.module_el8.4.0+2600+cefb5d4c
clang-libs
Fixed in 12.0.1-4.module_el8.4.0+2600+cefb5d4c
clang-resource-filesystem
Fixed in 12.0.1-4.module_el8.4.0+2600+cefb5d4c
clang-tools-extra
Fixed in 12.0.1-4.module_el8.4.0+2600+cefb5d4c
clippy
Fixed in 1.54.0-3.module_el8.5.0+2599+d655d86c
compiler-rt
Fixed in 12.0.1-1.module_el8.4.0+2600+cefb5d4c
cpp
Fixed in 8.5.0-4.el8_5.alma
gcc
Fixed in 8.5.0-4.el8_5.alma
gcc-c++
Fixed in 8.5.0-4.el8_5.alma
gcc-gdb-plugin
Fixed in 8.5.0-4.el8_5.alma
gcc-gfortran
Fixed in 8.5.0-4.el8_5.alma
gcc-offload-nvptx
Fixed in 8.5.0-4.el8_5.alma
gcc-plugin-devel
Fixed in 8.5.0-4.el8_5.alma
gcc-toolset-10-annobin
Fixed in 9.29-1.el8_5.2
gcc-toolset-10-binutils
Fixed in 2.35-8.el8_5.6
gcc-toolset-10-binutils-devel
Fixed in 2.35-8.el8_5.6
gcc-toolset-10-gcc
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-gcc-c++
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-gcc-gdb-plugin
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-gcc-gfortran
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-gcc-plugin-devel
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-libasan-devel
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-libatomic-devel
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-libitm-devel
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-liblsan-devel
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-libquadmath-devel
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-libstdc++-devel
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-libstdc++-docs
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-libtsan-devel
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-libubsan-devel
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-11-annobin-annocheck
Fixed in 9.85-1.el8_5.1
gcc-toolset-11-annobin-docs
Fixed in 9.85-1.el8_5.1
gcc-toolset-11-annobin-plugin-gcc
Fixed in 9.85-1.el8_5.1

58 further packages in AlmaLinux 8 not shown (first 40 listed).

Arch Linux

rust
Fixed in 1:1.56.1-1

Source: Arch Linux Security Tracker, the Arch Linux security team. Reformatted by exploit.cc.

CloudLinux 8

annobin
Fixed in 9.72-1.el8_5.2
annobin-annocheck
Fixed in 9.72-1.el8_5.2
binutils-devel
Fixed in 2.30-108.el8_5.1
cargo
Fixed in 1.54.0-3.module_el8.5.0+2599+d655d86c
cargo-doc
Fixed in 1.54.0-3.module_el8.5.0+2599+d655d86c
clang
Fixed in 12.0.1-4.module_el8.4.0+2600+cefb5d4c
clang-analyzer
Fixed in 12.0.1-4.module_el8.4.0+2600+cefb5d4c
clang-devel
Fixed in 12.0.1-4.module_el8.4.0+2600+cefb5d4c
clang-libs
Fixed in 12.0.1-4.module_el8.4.0+2600+cefb5d4c
clang-resource-filesystem
Fixed in 12.0.1-4.module_el8.4.0+2600+cefb5d4c
clang-tools-extra
Fixed in 12.0.1-4.module_el8.4.0+2600+cefb5d4c
clippy
Fixed in 1.54.0-3.module_el8.5.0+2599+d655d86c
compiler-rt
Fixed in 12.0.1-1.module_el8.4.0+2600+cefb5d4c
cpp
Fixed in 8.5.0-4.el8_5.alma
gcc
Fixed in 8.5.0-4.el8_5.alma
gcc-c++
Fixed in 8.5.0-4.el8_5.alma
gcc-gdb-plugin
Fixed in 8.5.0-4.el8_5.alma
gcc-gfortran
Fixed in 8.5.0-4.el8_5.alma
gcc-offload-nvptx
Fixed in 8.5.0-4.el8_5.alma
gcc-plugin-devel
Fixed in 8.5.0-4.el8_5.alma
gcc-toolset-10-annobin
Fixed in 9.29-1.el8_5.2
gcc-toolset-10-binutils
Fixed in 2.35-8.el8_5.6
gcc-toolset-10-binutils-devel
Fixed in 2.35-8.el8_5.6
gcc-toolset-10-gcc
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-gcc-c++
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-gcc-gdb-plugin
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-gcc-gfortran
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-gcc-plugin-devel
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-libasan-devel
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-libatomic-devel
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-libitm-devel
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-liblsan-devel
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-libquadmath-devel
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-libstdc++-devel
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-libstdc++-docs
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-libtsan-devel
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-10-libubsan-devel
Fixed in 10.3.1-1.2.el8_5
gcc-toolset-11-annobin-annocheck
Fixed in 9.85-1.el8_5.1
gcc-toolset-11-annobin-docs
Fixed in 9.85-1.el8_5.1
gcc-toolset-11-annobin-plugin-gcc
Fixed in 9.85-1.el8_5.1

58 further packages in CloudLinux 8 not shown (first 40 listed).

Derived from AlmaLinux 8. Partial coverage: only packages taken from AlmaLinux 8 are listed.

Debian 12

rustc
Fixed in 1.57.0+dfsg1-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

rustc
Fixed in 1.57.0+dfsg1-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

rustc
Fixed in 1.57.0+dfsg1-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 20.04 LTS

rustc
Fixed in 1.57.0+dfsg1+llvm-0ubuntu1~20.04.1

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 22.04 LTS

rustc
Fixed in 1.57.0+dfsg1+llvm-0ubuntu2

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.