What is CVE-2026-83608?

xmldom is a pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module. Prior to @xmldom/xmldom versions 0.8.15 and 0.9.12, and in xmldom version 0.6.0 and earlier, the DOCUMENT_TYPE_NODE branch in lib/dom.js validates publicId, systemId, and internalSubset under requireWellFormed: true but emits DocumentType.name verbatim. A name containing > or whitespace can terminate the declaration and inject sibling markup; the value can be supplied through createDocumentType() on the 0.8.x and unscoped lines or through a direct DocumentType.name property write on every affected line. The default path and legacy creation-time behavior remain permissive, while the vulnerable strict path fails to enforce an XML Name. This issue is fixed in @xmldom/xmldom versions 0.8.15 and 0.9.12; no fixed version is available for xmldom.

How severe is CVE-2026-83608?

CVE-2026-83608 has a CVSS 4.0 base score of 8.7, rated high severity.

Is CVE-2026-83608 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (48th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-83608?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-83608 published?

CVE-2026-83608 was published on 2026-09-01 and last updated on 2026-09-08.

CVE-2026-83608

CVE-2026-83608 is a high-severity vulnerability with a CVSS 4.0 base score of 8.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-91.

Key facts

Severity: High (CVSS 4.0 base score 8.7)
EPSS exploit prediction: 1% (48th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-91
Published: 2026-09-01
Last modified: 2026-09-08

Description

xmldom is a pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module. Prior to @xmldom/xmldom versions 0.8.15 and 0.9.12, and in xmldom version 0.6.0 and earlier, the DOCUMENT_TYPE_NODE branch in lib/dom.js validates publicId, systemId, and internalSubset under requireWellFormed: true but emits DocumentType.name verbatim. A name containing > or whitespace can terminate the <!DOCTYPE ...> declaration and inject sibling markup; the value can be supplied through createDocumentType() on the 0.8.x and unscoped lines or through a direct DocumentType.name property write on every affected line. The default path and legacy creation-time behavior remain permissive, while the vulnerable strict path fails to enforce an XML Name. This issue is fixed in @xmldom/xmldom versions 0.8.15 and 0.9.12; no fixed version is available for xmldom.

Frequently asked questions

What is CVE-2026-83608?: xmldom is a pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module. Prior to @xmldom/xmldom versions 0.8.15 and 0.9.12, and in xmldom version 0.6.0 and earlier, the DOCUMENT_TYPE_NODE branch in lib/dom.js validates publicId, systemId, and internalSubset under requireWellFormed: true but emits DocumentType.name verbatim. A name containing > or whitespace can terminate the <!DOCTYPE ...> declaration and inject sibling markup; the value can be supplied through createDocumentType() on the 0.8.x and unscoped lines or through a direct DocumentType.name property write on every affected line. The default path and legacy creation-time behavior remain permissive, while the vulnerable strict path fails to enforce an XML Name. This issue is fixed in @xmldom/xmldom versions 0.8.15 and 0.9.12; no fixed version is available for xmldom.
How severe is CVE-2026-83608?: CVE-2026-83608 has a CVSS 4.0 base score of 8.7, rated high severity.
Is CVE-2026-83608 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (48th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-83608?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-83608 published?: CVE-2026-83608 was published on 2026-09-01 and last updated on 2026-09-08.

References

Other CWE-91 (XML Injection) vulnerabilities

CVE-2021-4140 — Critical (CVSS 10.0): It was possible to construct specific XSLT markup that would be able to bypass an iframe sandbox. This vulnerability…
CVE-2026-103044 — Critical (CVSS 9.8): XML injection (aka blind XPath injection) vulnerability in The Wikimedia Foundation Mediawiki - EasyTimeline extension…
CVE-2023-43187 — Critical (CVSS 9.8): A remote code execution (RCE) vulnerability in the xmlrpc.php endpoint of NodeBB Inc NodeBB forum software prior to…
CVE-2019-19450 — Critical (CVSS 9.8): paraparser in ReportLab before 3.5.31 allows remote code execution because start_unichar in paraparser.py evaluates…
CVE-2021-37154 — Critical (CVSS 9.8): In ForgeRock Access Management (AM) before 7.0.2, the SAML2 implementation allows XML injection, potentially enabling a…
CVE-2020-29128 — Critical (CVSS 9.8): petl before 1.68, in some configurations, allows resolution of entities in an XML document.

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