CVE-2026-105219 Mammoth.js 1.3.0 before 1.12.3 ReDoS via Style Map Tokeniser
Attackers can cause a denial of service in applications using Mammoth.js by supplying a crafted .docx file that triggers a regular expression denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-105219?
CVE-2026-105219 is a high-severity denial of service vulnerability in mwilliamson mammoth.js, published on 4 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-1333
Which versions are affected by CVE-2026-105219?
How do I fix CVE-2026-105219?
No fix has been published for CVE-2026-105219 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-105219 being exploited?
There is no known exploitation of CVE-2026-105219 in the wild and no public exploit code.
Sources
Also known as GHSA-fp33-4hh4-xjj5.