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.

CVSS 4.0

8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS 3.1

7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

0.4% chance of exploitation in the next 30 days; higher than 29% of CVEs (scores of 2026-10-25)

CWE

CWE-1333

Published

2026-10-04

Modified

2026-10-06

Record from

the NVD, synced 2026-10-19

References

• https://github.com/mwilliamson/mammoth.js
• https://github.com/mwilliamson/mammoth.js/blob/1.12.2/lib/styles/parser/tokeniser.js#L6-L30
• https://github.com/mwilliamson/mammoth.js/commit/dc49225425c2c07de0a6dc3529f2386c82a032b4
• https://github.com/mwilliamson/mammoth.js/issues/487
• https://www.vulncheck.com/advisories/mammoth-js-1.3.0-before-1.12.3-redos-via-style-map-tokeniser

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