CVE-2021-42574: An issue was discovered in the Bidirectional Algorithm in the Unicode Specification through 14.0.
Noroxi assessment
Priority: Monitor (action score 37/100)
- Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
- Probability of exploitation in the next 30 days: 12.8% (FIRST EPSS); higher than 96.3% of all records.
- Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. Special conditions such as timing or configuration are required.
- Fixed version: annobin (AlmaLinux:8) 9.72-1.el8_5.2; annobin-annocheck (AlmaLinux:8) 9.72-1.el8_5.2; binutils-devel (AlmaLinux:8) 2.30-108.el8_5.1.
- Mentioned 4 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).
Low priority for now. Upgrade to annobin (AlmaLinux:8) 9.72-1.el8_5.2; annobin-annocheck (AlmaLinux:8) 9.72-1.el8_5.2; binutils-devel (AlmaLinux:8) 2.30-108.el8_5.1 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
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.
- BDU:2021-05328
- ALSA-2021:4585
- ALSA-2021:4586
- ALSA-2021:4587
- ALSA-2021:4590
- ALSA-2021:4591
- ALSA-2021:4592
- ALSA-2021:4593
- ALSA-2021:4594
- ALSA-2021:4595
- ALSA-2021:4649
- ALSA-2021:4743
- openSUSE-SU-2024:11650-1
- RHSA-2021:4033
- RHSA-2021:4034
- RHSA-2021:4035
- RHSA-2021:4036
- RHSA-2021:4037
- RHSA-2021:4038
- RHSA-2021:4039
- Published
- Nov 1, 2021
- Updated
- Jun 17, 2026
- EPSS
- 12.8% · 96th percentile
- CWE
- CWE-94
Report tools
Action score
37
Monitor
Low priority for now.
- CVSS
- 33 / 40 · 8.3 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 4 / 30 · 12.8%
CISA SSVC decision
- Exploitation
- proof of concept
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- Proof of concept exists, no weaponized module
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| unicode | unicode | cpe:2.3:a:unicode:unicode |
| fedoraproject | fedora | cpe:2.3:o:fedoraproject:fedora |
| starwindsoftware | starwind virtual san | cpe:2.3:a:starwindsoftware:starwind_virtual_san |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- fedoraproject fedora33
- fedoraproject fedora34
- fedoraproject fedora35
- starwindsoftware starwind virtual sanv8r13
- unicode unicodebefore 14.0.0
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:8 | annobin | before 9.72-1.el8_5.2 | 9.72-1.el8_5.2 |
| AlmaLinux:8 | annobin-annocheck | before 9.72-1.el8_5.2 | 9.72-1.el8_5.2 |
| AlmaLinux:8 | binutils-devel | before 2.30-108.el8_5.1 | 2.30-108.el8_5.1 |
| AlmaLinux:8 | cargo | before 1.54.0-3.module_el8.5.0+2599+d655d86c | 1.54.0-3.module_el8.5.0+2599+d655d86c |
| AlmaLinux:8 | cargo-doc | before 1.54.0-3.module_el8.5.0+2599+d655d86c | 1.54.0-3.module_el8.5.0+2599+d655d86c |
| AlmaLinux:8 | clang | before 12.0.1-4.module_el8.4.0+2600+cefb5d4c | 12.0.1-4.module_el8.4.0+2600+cefb5d4c |
| AlmaLinux:8 | clang-analyzer | before 12.0.1-4.module_el8.4.0+2600+cefb5d4c | 12.0.1-4.module_el8.4.0+2600+cefb5d4c |
| AlmaLinux:8 | clang-devel | before 12.0.1-4.module_el8.4.0+2600+cefb5d4c | 12.0.1-4.module_el8.4.0+2600+cefb5d4c |
| AlmaLinux:8 | clang-libs | before 12.0.1-4.module_el8.4.0+2600+cefb5d4c | 12.0.1-4.module_el8.4.0+2600+cefb5d4c |
| AlmaLinux:8 | clang-resource-filesystem | before 12.0.1-4.module_el8.4.0+2600+cefb5d4c | 12.0.1-4.module_el8.4.0+2600+cefb5d4c |
| AlmaLinux:8 | clang-tools-extra | before 12.0.1-4.module_el8.4.0+2600+cefb5d4c | 12.0.1-4.module_el8.4.0+2600+cefb5d4c |
| AlmaLinux:8 | clippy | before 1.54.0-3.module_el8.5.0+2599+d655d86c | 1.54.0-3.module_el8.5.0+2599+d655d86c |
| AlmaLinux:8 | compiler-rt | before 12.0.1-1.module_el8.4.0+2600+cefb5d4c | 12.0.1-1.module_el8.4.0+2600+cefb5d4c |
| AlmaLinux:8 | cpp | before 8.5.0-4.el8_5.alma | 8.5.0-4.el8_5.alma |
| AlmaLinux:8 | gcc | before 8.5.0-4.el8_5.alma | 8.5.0-4.el8_5.alma |
| AlmaLinux:8 | gcc-c++ | before 8.5.0-4.el8_5.alma | 8.5.0-4.el8_5.alma |
| AlmaLinux:8 | gcc-gdb-plugin | before 8.5.0-4.el8_5.alma | 8.5.0-4.el8_5.alma |
| AlmaLinux:8 | gcc-gfortran | before 8.5.0-4.el8_5.alma | 8.5.0-4.el8_5.alma |
| AlmaLinux:8 | gcc-offload-nvptx | before 8.5.0-4.el8_5.alma | 8.5.0-4.el8_5.alma |
| AlmaLinux:8 | gcc-plugin-devel | before 8.5.0-4.el8_5.alma | 8.5.0-4.el8_5.alma |
| AlmaLinux:8 | gcc-toolset-10-annobin | before 9.29-1.el8_5.2 | 9.29-1.el8_5.2 |
| AlmaLinux:8 | gcc-toolset-10-binutils | before 2.35-8.el8_5.6 | 2.35-8.el8_5.6 |
| AlmaLinux:8 | gcc-toolset-10-binutils-devel | before 2.35-8.el8_5.6 | 2.35-8.el8_5.6 |
| AlmaLinux:8 | gcc-toolset-10-gcc | before 10.3.1-1.2.el8_5 | 10.3.1-1.2.el8_5 |
+96
Same product
unicode: all recordsOther highest-scoring records for the same primary product.
- CVE-2021-42694An issue was discovered in the character definitions of the Unicode Specification through 14.0.34Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| almalinux:gcc-toolset-10-gcc | 10.3.1-1.2.el8_5 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:gcc-toolset-10-gcc-c++ | 10.3.1-1.2.el8_5 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:gcc-toolset-10-gcc-gdb-plugin | 10.3.1-1.2.el8_5 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:gcc-toolset-10-gcc-gfortran | 10.3.1-1.2.el8_5 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:gcc-toolset-10-gcc-plugin-devel | 10.3.1-1.2.el8_5 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:gcc-toolset-10-libasan-devel | 10.3.1-1.2.el8_5 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:gcc-toolset-10-libatomic-devel | 10.3.1-1.2.el8_5 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:gcc-toolset-10-libitm-devel | 10.3.1-1.2.el8_5 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:gcc-toolset-10-liblsan-devel | 10.3.1-1.2.el8_5 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:gcc-toolset-10-libquadmath-devel | 10.3.1-1.2.el8_5 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:gcc-toolset-10-libstdc++-devel | 10.3.1-1.2.el8_5 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:gcc-toolset-10-libstdc++-docs | 10.3.1-1.2.el8_5 · AlmaLinux:8 | Package registry (OSV) |
| alpine:chromium-rust | 1.56.1-r0 · Alpine:v3.24 | Package registry (OSV) |
| alpine:rust | 1.56.1-r0 · Alpine:v3.19 | Package registry (OSV) |
| debian:rustc | 1.57.0+dfsg1-1 · Debian:12 | Package registry (OSV) |
| opensuse:rust1.56 | 1.56.1-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:binutils | 0:2.27-44.base.el7_9.1 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:binutils-debuginfo | 0:2.27-44.base.el7_9.1 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:binutils-devel | 0:2.27-44.base.el7_9.1 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:devtoolset-10-gcc | 0:10.2.1-11.2.el7 · Red Hat:rhel_software_collections:3::el7 | Package registry (OSV) |
| red hat:devtoolset-10-gcc-c++ | 0:10.2.1-11.2.el7 · Red Hat:rhel_software_collections:3::el7 | Package registry (OSV) |
| red hat:devtoolset-10-gcc-debuginfo | 0:10.2.1-11.2.el7 · Red Hat:rhel_software_collections:3::el7 | Package registry (OSV) |
| red hat:devtoolset-10-gcc-gdb-plugin | 0:10.2.1-11.2.el7 · Red Hat:rhel_software_collections:3::el7 | Package registry (OSV) |
| red hat:devtoolset-10-gcc-gfortran | 0:10.2.1-11.2.el7 · Red Hat:rhel_software_collections:3::el7 | Package registry (OSV) |
| red hat:devtoolset-10-gcc-plugin-devel | 0:10.2.1-11.2.el7 · Red Hat:rhel_software_collections:3::el7 | Package registry (OSV) |
| red hat:devtoolset-10-libasan-devel | 0:10.2.1-11.2.el7 · Red Hat:rhel_software_collections:3::el7 | Package registry (OSV) |
| red hat:devtoolset-10-libatomic-devel | 0:10.2.1-11.2.el7 · Red Hat:rhel_software_collections:3::el7 | Package registry (OSV) |
| red hat:devtoolset-10-libgccjit | 0:10.2.1-11.2.el7 · Red Hat:rhel_software_collections:3::el7 | Package registry (OSV) |
| rocky linux:annobin | 0:9.72-1.el8_5.2 · Rocky Linux:8 | Package registry (OSV) |
| rocky linux:binutils | 0:2.30-108.el8_5.1 · Rocky Linux:8 | Package registry (OSV) |
+10
Exploit status
Proof of concept available
A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.
Evidence
- Proof-of-concept repository on GitHub ×11
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Proof-of-concept repository on GitHub | stars:1 | 2021-11-01 |
| Proof-of-concept repository on GitHub | stars:1 | 2021-11-01 |
| Proof-of-concept repository on GitHub | stars:8 | 2021-11-02 |
| Proof-of-concept repository on GitHub | stars:6 | 2021-11-06 |
| Proof-of-concept repository on GitHub | stars:0 | 2021-11-25 |
| Proof-of-concept repository on GitHub | stars:1 | 2021-12-11 |
| Proof-of-concept repository on GitHub | stars:3 | 2023-01-31 |
| Proof-of-concept repository on GitHub | stars:5 | 2026-03-21 |
| Proof-of-concept repository on GitHub | stars:5 | 2026-08-16 |
| Proof-of-concept repository on GitHub | stars:0 | 2026-10-16 |
| Proof-of-concept repository on GitHub | stars:0 | 2026-10-28 |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- First PoCsame day
- Published
- TodayNov 7, 2026+1833 d
No history yet (it accumulates with the daily EPSS job).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
National notice (Türkiye Cybersecurity Directorate / USOM)
Official security notices citing this record; remediation advice is on the agency's page.
- TR-22-0222 · Mar 15, 2022(RedHat Güvenlik Güncellemesi)
- TR-22-0113 · Feb 4, 2022(RedHat Güvenlik Güncellemesi)
- TR-22-0097 · Jan 28, 2022(RedHat Güvenlik Güncellemesi)
- TR-21-0881 · Nov 2, 2021(RedHat Güvenlik Güncellemesi)
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- A user must open a link or visit a page.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
Impact can extend beyond the vulnerable component (scope changes).
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-94 · Improper Control of Generation of Code ('Code Injection')CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (13 more)Show less
- www.openwall.com/lists/oss-security/2021/11/01/6
- www.openwall.com/lists/oss-security/2021/11/02/10
- www.unicode.org/versions/Unicode14.0.0/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IH2RG5YTR6ZZOLUV3EUPZEIJR7XHJLVD/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LQNTFF24ROHLVPLUOEISBN3F7QM27L4U/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QUPA37D57VPTDLSXOOGF4UXUEADOC4PQ/
- security.gentoo.org/glsa/202210-09
- www.kb.cert.org/vuls/id/999008
- www.starwindsoftware.com/security/sw-20220804-0002/
- www.unicode.org/reports/tr31/
- www.unicode.org/reports/tr36/
- www.unicode.org/reports/tr39/
- www.unicode.org/reports/tr9/tr9-44.html#HL4
Vendor advisories and official records. Exploit/PoC links are deliberately left out.