TI-2026-25835 Aliases CVE-2026-33438

Stirling-PDF vulnerable to DoS via add-watermark

MEDIUM 62CWE-770Published 2026-03-26 · Updated 2026-03-26

Key facts

Attack vector: Network
Privileges required: Low
User interaction: None
Attack complexity: Low
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-770.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00413 35th percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Fixed Stirling-PDF (Stirling-Tools): 2.5.2

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Stirling-Tools	Stirling-PDF	2.1.5 to before 2.5.2	2.5.2	Patch available	CNA

Stirling-PDF VendorStirling-Tools Affected 2.1.5 to before 2.5.2 Fixed in 2.5.2 Patch available CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:stirling:stirling_pdf::::::::	2.1.5 to before 2.5.2	Vulnerable	Stirling-Tools

cpe:2.3:a:stirling:stirling_pdf:*:*:*:*:*:*:*:* Versions 2.1.5 to before 2.5.2 Vulnerable ·Stirling-Tools

Remediation

Fix · CNA Stirling-PDF (Stirling-Tools) Fixed in 2.5.2

Timeline

2026-10-02 Threatist record created from CVE-2026-33438

References

Exploit 1

https://github.com/Stirling-Tools/Stirling-PDF/security/advisories/GHSA-3932-2rfq-87xm

TI-2026-22007 Stirling-PDF Zip Slip: Arbitrary File Write via Path Traversal in Markdown-to-PDF ZIP Extraction CVSS 3.1HIGH 8.1
TI-2026-30134 Stirling-PDF: Reflected XSS through crafted PDF metadata fields (Title and Author) CVSS 3.1MEDIUM 6.1
TI-2026-26396 Stirling-PDF has Stored Cross Site Scripting (XSS) via EML-to-HTML Export CVSS 3.1MEDIUM 6.1

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences