How to Fix CVE-2026-3777: Foxit PDF Editor (Bundle Sibling)

*By Sai Kiran Pandrala*

Last verified: 2026-05-25

CVE-2026-3777 is a sibling vulnerability in the same Foxit Software Inc. Foxit PDF Editor advisory bundle as CVE-2026-3774. The same patched build closes every CVE in the bundle, so the remediation procedure for CVE-2026-3777 matches the primary write-up.

What is different about CVE-2026-3777?

The application does not properly validate the lifetime and validity of internal view cache pointers after JavaScript changes the document zoom and page state. When a script modifies the zoom property and then triggers a page change, the original view object may be destroyed while stale pointers are still kept and later dereferenced, which under crafted JavaScript and document structures can lead to a use-after-free condition and potentially allow arbitrary code execution.

Impact is consistent with the bundle: remote code execution on the affected system. The patched build closes every code path in the advisory in one update.

How to fix CVE-2026-3777

Apply the patched build per the primary write-up: How to Fix CVE-2026-3774.

For a quick check, confirm the running version of Foxit PDF Editor:

# Confirm the installed version via your package manager
dpkg -l | grep -i foxit   # Debian/Ubuntu
rpm -qa | grep -i foxit   # RHEL/CentOS/Rocky

Frequently asked questions

Is CVE-2026-3777 being actively exploited?

Not at the time of writing. It is not listed in CISA's Known Exploited Vulnerabilities catalog. That status can change, so monitor the vendor advisory and the KEV catalog if the system is exposed.

How severe is CVE-2026-3777?

CVSS rates it 5.5 (Medium). Use that score to set your patch priority alongside the other items in your queue.

Do I have to take Foxit PDF Editor offline to apply the patch?

It depends on the deployment. High-availability or clustered installs can usually patch one node at a time with no full outage. Standalone installs typically need a short restart. Always follow the vendor's documented upgrade steps.

What if my vulnerability scanner still flags CVE-2026-3777 after I patch?

Re-run the scan after a service restart, then confirm the scanner's plugin set is up to date. Some scanners detect by banner version only and lag the official fix metadata by a release.

References

• Official vendor advisory: https://www.foxit.com/support/security-bulletins.html
• NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2026-3777
• CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
• Primary write-up: How to Fix CVE-2026-3774

*Written by Sai Kiran Pandrala. Last verified 2026-05-25. Part of the Foxit Software Inc. Foxit PDF Editor advisory bundle. Full procedure at how-to-fix-cve-2026-3774.*