CVE-2024-34078Network attack vector

Cross-site scripting via late Unicode normalization

Published May 6, 2024 · Updated Aug 26, 2024

Cross-site scripting in matthiask HTML Sanitizer before 2.4.2 allows remote attackers to inject arbitrary HTML via crafted Unicode. Sanitizer.sanitize performs NFKC normalization after parsing and allowlist filtering, converting full-width Unicode delimiters into executable HTML only after validation. Exploitation requires an application to accept attacker-controlled markup with the default setting and a user to render the sanitized output.

CVSS severity6.1
Medium
EPSS probability0.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in matthiask HTML Sanitizer before 2.4.2 allows remote attackers to inject arbitrary HTML via crafted Unicode. Sanitizer.sanitize performs NFKC normalization after parsing and allowlist filtering, converting full-width Unicode delimiters into executable HTML only after validation. Exploitation requires an application to accept attacker-controlled markup with the default setting and a user to render the sanitized output.

The record

CVE
CVE-2024-34078
Published
May 6, 2024
Updated
Aug 26, 2024
Vendor
in2code GmbH
Product
HTML Sanitizer
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 6, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 26, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.4.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

in2code GmbH · HTML Sanitizerversion=< 2.4.2

Published CVSS scores

6.1GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript/JScript

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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