# CVE-2026-91812: Foxit PDF Editor/Reader update mechanism certificate validation bypass

Source: https://junglewise.ai/threats/cve-2026-91812-a-vulnerability-in-foxit-pdf-editor-reader-s-update-mechanism  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-23. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-91812 · Severity: high · CVSS 7.9 · Published 2026-09-23

Foxit PDF Editor and Reader are widely used document processing applications. An attacker positioned between a user and Foxit's update servers could intercept updates and inject malicious code, which would then execute with system-level privileges when the application installs the tampered update. This could lead to full system compromise and data theft.

Technologies: [Foxit PDF Editor](https://junglewise.ai/threats/technologies/pdf-editor), [Foxit PDF Reader](https://junglewise.ai/threats/technologies/pdf-reader). Vendors: [Foxit](https://junglewise.ai/threats/vendors/foxit).

## Quick answers

**Is CVE-2026-91812 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-91812 being exploited in the wild.

**How severe is CVE-2026-91812?** High severity, with a CVSS score of 7.9, published 23 September 2026.

**Which products and versions are affected?** Foxit PDF Editor 2026.2.0.39747 and all previous 2026.x versions, 2025.3.0.35737 and all previous 2025.x versions, 2024.4.1.27687 and all previous 2024.x versions, 2023.3.0.23028 and all previous 2023.x versions, 14.0.7.33751 and all previous 14.x versions, 13.2.6.24111 and earlier; Foxit PDF Reader 2026.2.0.39747 and earlier.

**Is there a fix for CVE-2026-91812?** A patch was published on 2026-09-23: Foxit PDF Reader 2026.2.1 and Foxit PDF Editor 2026.2.1/14.0.8 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-91812 attacked?** It is attacked over the network or from the adjacent network.

**Am I affected by CVE-2026-91812?** Check whether you run Foxit PDF Editor or Foxit PDF Reader at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability exists in the update mechanism's handling of SSL/TLS certificate validation and package integrity checks. An attacker on the network path (man-in-the-middle) can bypass these protections to serve malicious packages during the update process. No user interaction beyond initiating an update is required; the attack succeeds if the victim's system checks for or performs an automatic update over an insecure or compromised network.

## Affected products

- Foxit PDF Reader 2026.2.0.39747 and earlier
- Foxit PDF Editor 2026.2.0.39747 and all previous 2026.x versions, 2025.3.0.35737 and all previous 2025.x versions, 2024.4.1.27687 and all previous 2024.x versions, 2023.3.0.23028 and all previous 2023.x versions, 14.0.7.33751 and all previous 14.x versions, 13.2.6.24111 and earlier

## Timeline

- 2026-09-23: disclosed: CVE-2026-91812 disclosed
- 2026-09-23: patched: Foxit PDF Reader 2026.2.1 and Foxit PDF Editor 2026.2.1/14.0.8 released

## References

- [https://www.foxit.com/support/security-bulletins.html](https://www.foxit.com/support/security-bulletins.html)

## Related threats

- [Foxit PDF Editor use-after-free in JavaScript annotation handling](https://junglewise.ai/threats/cve-2026-91818-a-use-after-free-vulnerability-exists-in-foxit-pdf-editor-reader)
- [Foxit PDF Editor heap-based out-of-bounds read in JavaScript string handling](https://junglewise.ai/threats/cve-2026-91817-a-heap-based-out-of-bounds-read-vulnerability-exists-in-foxit-pdf)
- [Foxit PDF Editor use-after-free in annotation handling](https://junglewise.ai/threats/cve-2026-91816-a-use-after-free-vulnerability-exists-in-foxit-pdf-editor-reader)
- [Foxit PDF Editor/Reader out-of-bounds write in JPEG2000 decoding](https://junglewise.ai/threats/cve-2026-91815-foxit-pdf-editor-reader-does-not-perform-sufficient-verification)
- [Foxit PDF Editor and Reader signature validation bypass in incremental updates](https://junglewise.ai/threats/cve-2026-91814-a-signature-validation-vulnerability-exists-in-foxit-pdf-editor)