Vulnerability · Published Mar 26, 2026 · Assigned by GitHub_M
CVE-2026-33438Stirling-PDF vulnerable to DoS via add-watermark
Medium 6.5
In plain English
A medium-severity resource allocation without limits in Stirling-PDF from Stirling-Tools. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 36% of all known vulnerabilities).
Official description
Stirling-PDF is a locally hosted web application that allows you to perform various operations on PDF files. Versions starting in 2.1.5 and prior to 2.5.2 have Denial of Service (DoS) vulnerability in the Stirling-PDF watermark functionality (`/api/v1/security/add-watermark` endpoint). The vulnerability allows authenticated users to cause resource exhaustion and server crashes by providing extreme values for the `fontSize` and `widthSpacer` parameters. Version 2.5.2 patches the issue.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Stirling-Tools | Stirling-PDF | >= 2.1.5, < 2.5.2 |
Weakness: CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H