CVE-2026-103387 garycourt uri-js Mailto Header mailto.ts URI.parse uncaught exception
Remote attackers can cause a denial of service via uncaught exceptions in the uri-js library's mailto header parser.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-103387?
CVE-2026-103387 is a medium-severity denial of service vulnerability in garycourt uri-js, published on 30 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
A weakness has been identified in garycourt uri-js up to 4.4.1. This affects the function URI.parse of the file src/schemes/mailto.ts of the component Mailto Header Handler. This manipulation of the argument to causes uncaught exception. The attack may be initiated remotely. The exploit has been made available to the public and could be used for attacks. The project was informed of the problem early through an issue report but has not responded yet.
Weakness: CWE-248
Which versions are affected by CVE-2026-103387?
How do I fix CVE-2026-103387?
No fix has been published for CVE-2026-103387 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-2026-103387 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-103387 exists.
Sources
Also known as AZL-105351, DEBIAN-CVE-2026-103387, GHSA-cw9r-3wqp-32hm, UBUNTU-CVE-2026-103387.