What is CVE-2026-33438?

CVE-2026-33438 is a medium-severity vulnerability in Stirling Pdf, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 6.5/10. Published 2026-03-26.

How severe is CVE-2026-33438?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Resource exhaustion in Stirling Pdf

CVE-2026-33438

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.

Published 2026-03-26 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.004 (36.1th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 36th percentile — 36.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: +0.000

Affected products

Stirling Pdf
Stirling-Tools Stirling-Pdf — versions >= 2.1.5, < 2.5.2

Weakness classification (CWE)

CWE-770 — Allocation of Resources Without Limits or Throttling

References

github.com/Stirling-Tools/Stirling-PDF/security/advisories/GHSA-3932-2rfq-87xm (Exploit, Vendor Advisory)

Frequently asked questions

What is CVE-2026-33438?: CVE-2026-33438 is a medium-severity vulnerability in Stirling Pdf, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 6.5/10. Published 2026-03-26.
How severe is CVE-2026-33438?: Medium severity. CVSS v3 base score is 6.5 out of 10.