Medium exploit reference

CVE-2026-65902 — DOMPurify before 3.4.7 Hook Mutation Pollution via allowedTags

DOMPurify before 3.4.7 (affected versions <= 3.4.5) passes direct references to the module-level DEFAULT_ALLOWED_TAGS and DEFAULT_ALLOWED_ATTR sets to the uponSanitizeElement and uponSanitizeAttribute hooks via data.allowedTags / data.allowedAttributes when sanitize is called without an explicit cfg.ALLOWED_TAGS / cfg.ALLOWED_ATTR array. A hook that mutates these fields permanently widens the default allow-lists for the lifetime of the DOMPurify instance, so all subsequent default-config sanitize calls inherit the widened defaults and attacker payloads using the poisoned tag/attribute name survive sanitization. removeAllHooks(), clearConfig(), and passing a fresh cfg do not recover the state; only constructing a new DOMPurify instance does.

Published Jul 23, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: VulnCheck

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

Technical severity (medium)+3
CISA SSVC: exploitation "poc"+5

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

—

No EPSS score.

Affects

Cure53

Dompurify

CVSS base

6.1

Medium · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

Proof of concept

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

Documented patch — github.com (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Cure53 Dompurify).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
Apply the fixed version or the patch documented under Remediation.
Exploitation requires user interaction: tighten email/web filtering and warn affected users.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Cure53	Dompurify	< 3.4.7	Vulnerable	NIST National Vulnerability Database
Cure53	Dompurify	< 3.4.7	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
5.3	CVSS 4.0	Medium	—	—	disclosure@vulncheck.com via NIST National Vulnerability Database
5.3	CVSS 4.0	Medium	—	—	VulnCheck via CVE Program (cve.org) e CISA ADP
6.1	CVSS 3.1	Medium	2.8	2.7	disclosure@vulncheck.com via NIST National Vulnerability Database
6.1	CVSS 3.1	Medium	—	—	VulnCheck via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N (score shown at the top: disclosure@vulncheck.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-501

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Affected products added · cure53/dompurify
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 15, 2026
Fix documented
Oct 15, 2026 · NIST National Vulnerability Database
CVSS changed · 6.1
Oct 15, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Jul 23, 2026 · VulnCheck

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

3 on the record

github.com/cure53/DOMPurify/commit/7996f1dc78eb8b7922388aed75d94a9f8fad9a36
Patch, patch, NIST National Vulnerability Database
github.com/cure53/DOMPurify/security/advisories/GHSA-76mc-f452-cxcm
Exploit, Third Party Advisory, vendor-advisory, NIST National Vulnerability Database
www.vulncheck.com/advisories/dompurify-before-hook-mutation-pollution-via-allowedtags
Third Party Advisory, third-party-advisory, NIST National Vulnerability Database

Elsewhere on this site

Cure53
every CVE for this vendor

CWE-501
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-109345 DOMPurify before 3.4.16 XSS via IN_PLACE Returned Rawtext Root 3d
Medium CVE-2026-109344 DOMPurify from 3.4.13 before 3.4.16 DOM XSS via IN_PLACE afterSanitize Hooks 3d
Medium CVE-2026-66010 DOMPurify before 3.4.12 Hook Bypass via CUSTOM_ELEMENT_HANDLING Jul 24, 2026
Medium CVE-2026-65914 DOMPurify before 3.3.2 Mutation XSS via Re-Contextualization Jul 23, 2026
Medium CVE-2026-65911 DOMPurify before 3.4.0 XSS via ADD_ATTR/ADD_TAGS State Leakage Jul 23, 2026
Medium CVE-2026-65912 DOMPurify before 3.3.2 URI Validation Bypass via ADD_ATTR Jul 23, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No FIRST EPSS score.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-65902 is "DOMPurify before 3.4.7 Hook Mutation Pollution via allowedTags", rated Medium. It affects Dompurify (Cure53); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.1 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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