# CVE-2026-91793: Foxit PDF Reader use-after-free in annotation processing

Source: https://junglewise.ai/threats/cve-2026-91793-when-opening-a-specially-crafted-pdf-foxit-pdf-editor-reader  
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-2026-91793 · Severity: high · CVSS 7.8 · Published 2026-09-23

Foxit PDF Reader and PDF Editor are widely used applications for viewing and editing PDF documents. When a user opens a specially crafted PDF file, malformed annotation data triggers a use-after-free vulnerability in the annotation rendering engine, causing the application to crash. While the advisory does not indicate active exploitation, the attack requires only user interaction to open a malicious file.

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-2026-91793 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-91793 being exploited in the wild.

**How severe is CVE-2026-91793?** High severity, with a CVSS score of 7.8, 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-2026-91793?** A patch was published on 2026-09-23: Fixed in Foxit PDF Reader 2026.2.1 and Foxit PDF Editor 2026.2.1/14.0.8 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-91793 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-91793?** 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

A use-after-free vulnerability exists in the annotation appearance reconstruction code when processing rich-text attributes with malformed font data. The vulnerability is triggered when JavaScript actions modify annotations containing malicious font references, and the renderer accesses freed memory during subsequent appearance reconstruction. Exploitation requires a user to open a crafted PDF file; no authentication or network access is needed.

## 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
- 2026-09-23: patched: Fixed in Foxit PDF Reader 2026.2.1 and Foxit PDF Editor 2026.2.1/14.0.8

## 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)