CVE-2021-42574Public exploitNetwork attack vector

Code injection via bidirectional control reordering

Published Nov 1, 2021 · Updated Aug 4, 2024

Code injection in the Unicode Bidirectional Algorithm through 14.0 allows attackers to conceal malicious source code via bidirectional controls. Embedded directional controls alter the displayed token order without changing the logical sequence processed by a compiler or interpreter. Exploitation requires influence over source code and human review through a renderer that displays the crafted order, enabling hidden logic to enter a codebase.

CVSS severity8.3
High
EPSS probability12.88%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code injection in the Unicode Bidirectional Algorithm through 14.0 allows attackers to conceal malicious source code via bidirectional controls. Embedded directional controls alter the displayed token order without changing the logical sequence processed by a compiler or interpreter. Exploitation requires influence over source code and human review through a renderer that displays the crafted order, enabling hidden logic to enter a codebase.

The record

CVE
CVE-2021-42574
Published
Nov 1, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-94, T1027
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 1, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.1NVDAV:N/AC:H/Au:N/C:P/I:P/A:P
8.5Amazon LinuxCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
8.3NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-94Improper Control of Generation of Code ('Code Injection')
T1027Obfuscated Files or Information

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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