CVE-2026-41240Public exploitNetwork attack vector

HTML injection via skipped forbidden-tag check

Published Apr 23, 2026 · Updated Apr 23, 2026

Cross-site scripting in Cure53 DOMPurify before 3.4.0 allows remote attackers to preserve forbidden elements in sanitized markup. In _sanitizeElements, a true function-based ADD_TAGS predicate short-circuits the condition before FORBID_TAGS is evaluated, retaining blocked iframe, object, embed, or form elements and allowed attributes. Exploitation requires an application to combine function-based ADD_TAGS with FORBID_TAGS and render attacker-controlled sanitized output, enabling external-content or form-action injection.

CVSS severity6.0
Medium
EPSS probability0.31%
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 Cure53 DOMPurify before 3.4.0 allows remote attackers to preserve forbidden elements in sanitized markup. In _sanitizeElements, a true function-based ADD_TAGS predicate short-circuits the condition before FORBID_TAGS is evaluated, retaining blocked iframe, object, embed, or form elements and allowed attributes. Exploitation requires an application to combine function-based ADD_TAGS with FORBID_TAGS and render attacker-controlled sanitized output, enabling external-content or form-action injection.

The record

CVE
CVE-2026-41240
Published
Apr 23, 2026
Updated
Apr 23, 2026
Vendor
Cure53
Product
DOMPurify
Classifications
CWE-79, CWE-183, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 23, 2026Record 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=< 3.4.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Cure53 · DOMPurifyversion=< 3.4.0

Published CVSS scores

6.0GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
6.1NIST NVDCVSS: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 exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-183Permissive List of Allowed Inputs
T1203Exploitation for Client Execution

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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