Vulnerability in Mwilliamson Mammoth.js
CVE-2026-105219
Mammoth.js 1.3.0 before 1.12.3 contains a regular expression denial of service vulnerability in the style map tokeniser in lib/styles/parser/tokeniser.js due to overlapping regex alternatives. Attackers can supply a crafted .docx with an unterminated quoted string of repeated backslash escapes in mammoth/style-map to block the Node.js event loop.
Vulnerability class: ReDoS (Regular Expression Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/mwilliamson/mammoth.js/issues/487 (issue-tracking)
- github.com/mwilliamson/mammoth.js/commit/dc49225425c2c07de0a6dc3529f2386c82a032… (patch)
- github.com/mwilliamson/mammoth.js/blob/1.12.2/lib/styles/parser/tokeniser.js (technical-description)
- github.com/mwilliamson/mammoth.js (product)
- www.vulncheck.com/advisories/mammoth-js-1.3.0-before-1.12.3-redos-via-style-map… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-105219?
- CVE-2026-105219 is a high-severity vulnerability in Mwilliamson Mammoth.js, classified under Inefficient Regular Expression Complexity. CVSS score: 7.5/10. Published 2026-10-04.
- How severe is CVE-2026-105219?
- High severity. CVSS v3 base score is 7.5 out of 10.