CVE-2021-39307: PDFTron's WebViewer UI 8.0 or below renders dangerous URLs as hyperlinks in supported documents, including Jav

Q: How do I fix CVE-2021-39307?

webviewer ui: upgrade to newer than 8.0. Exact commands for each OS are on this page.

Q: Is CVE-2021-39307 being exploited?

CVE-2021-39307 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-39307 affect?

CVE-2021-39307 affects webviewer ui. Severity is medium (CVSS 6.1). PDFTron's WebViewer UI 8.0 or below renders dangerous URLs as hyperlinks in supported documents, including JavaScript URLs, allowing the execution of arbitrary JavaScript code.

Q: How urgent is CVE-2021-39307?

Priority 43/100. Public exploit reference

This month

MEDIUM 6.1UPGRADE

CVE-2021-39307 is a medium-severity flaw (CVSS 6.1) affecting webviewer ui. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

PDFTron's WebViewer UI 8.0 or below renders dangerous URLs as hyperlinks in supported documents, including JavaScript URLs, allowing the execution of arbitrary JavaScript code.

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	1.1% (top 34%)
CISA exploited list	No
Weakness	CWE-79
Published	2021-09-15
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: pdftron

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

Am I affected?

Timeline

2021-09-15 13:15 UTCPublished CVE record published
2026-06-17 04:03 UTCUpdated Record last modified

pdftron webviewer ui UPGRADE

Affected: <= 8.0

Fixed in: newer than 8.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy webviewer-ui || rpm -q webviewer-ui || webviewer-ui --version

2. UPGRADE to newer than 8.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade webviewer-ui

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade webviewer-ui

Note

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

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-2021-39307?

webviewer ui: upgrade to newer than 8.0. Exact commands for each OS are on this page.

Is CVE-2021-39307 being exploited?

CVE-2021-39307 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-2021-39307 affect?

CVE-2021-39307 affects webviewer ui. Severity is medium (CVSS 6.1). PDFTron's WebViewer UI 8.0 or below renders dangerous URLs as hyperlinks in supported documents, including JavaScript URLs, allowing the execution of arbitrary JavaScript code.

How urgent is CVE-2021-39307?

Priority 43/100. Public exploit reference

References

← Back to latest CVEs