CVE-2026-33438: Stirling-PDF is a locally hosted web application that allows you to perform various operations on PDF files

Routine

MEDIUM 6.5UPGRADE

CVE-2026-33438 is a medium-severity flaw (CVSS 6.5) affecting stirling pdf. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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` param

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.4% (top 65%)
CISA exploited list	No
Weakness	CWE-770
Published	2026-03-26
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: stirling

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-26 17:16 UTCPublished CVE record published
2026-06-17 10:37 UTCUpdated Record last modified

stirling stirling pdf UPGRADE

Affected: >= 2.1.5 and < 2.5.2

Fixed in: 2.5.2

Safe to downgrade to: a release before 2.1.5

1. Check installed version

apt-cache policy stirling-pdf || rpm -q stirling-pdf || stirling-pdf --version

2. UPGRADE to 2.5.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade stirling-pdf

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade stirling-pdf

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.1.5 (Debian / Ubuntu)

apt-cache madison stirling-pdf sudo apt install stirling-pdf=<VERSION_BEFORE_2.1.5> sudo apt-mark hold stirling-pdf

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list stirling-pdf sudo dnf downgrade stirling-pdf-<VERSION_BEFORE_2.1.5> sudo dnf versionlock add stirling-pdf

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-33438?

stirling pdf: upgrade to 2.5.2. Exact commands for each OS are on this page.

Is CVE-2026-33438 being exploited?

CVE-2026-33438 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-33438 affect?

CVE-2026-33438 affects stirling pdf. Severity is medium (CVSS 6.5). 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 functionalit

How urgent is CVE-2026-33438?

Priority 37/100. Public exploit reference

Related CVEs

CVE-2026-33436 LOW 3.1 UPGRADE Stirling-PDF is a locally hosted web application that facilitates various operations on PDF files
CVE-2026-41580 MEDIUM 6.1 UPGRADE Stirling-PDF is a locally hosted web application that facilitates various operations on PDF files
CVE-2026-34071 MEDIUM 5.4 DOWNGRADE Stirling-PDF is a locally hosted web application that allows you to perform various operations on PDF files
CVE-2026-27625 HIGH 8.1 UPGRADE Stirling-PDF is a locally hosted web application that performs various operations on PDF files

References

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