Parsing logic flaws cause non-signature data to be misidentified as valid signatures when…
CVE-2026-5941 is a high-severity improper input validation vulnerability in Foxit PDF Editor from Foxit, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. Affected Foxit PDF Editor versions: Versions 2026.1 and earlier; Versions 14.0.3 and earlier. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.17% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update PDF Editor to 14.0.4 or 2026.1.1, whichever matches your release line, or a later version.
- Update PDF Reader to 2026.1.1 or a later version.
- Read the advisory on foxit.com for workarounds and exact fixed builds.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Foxit Software | Foxit PDF Editor | Versions 2026.1 and earlier; Versions 14.0.3 and earlier | Not stated |
| Foxit Software | Foxit PDF Reader | Versions 2026.1 and earlier | Not stated |
| Foxit | PDF Editor | 14.0.0 up to, but not including, 14.0.4; 2023.0.0 up to, but not including, 2026.1.1 | 14.0.4, 2026.1.1 |
| Foxit | PDF Reader | before 2026.1.1 | 2026.1.1 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CNA |
| CVSS 3.1 | 7.1 | High | NVD |
Official description
Parsing logic flaws cause non-signature data to be misidentified as valid signatures when processing malformed form field hierarchies, leading to invalid memory writes and program crashes during internal data structure construction.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
How developers prevent this class of flaw
- Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build recognizers for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of allowing parser code to be scattered throughout the program, where it could be subject to errors or inconsistencies that create weaknesses.
- Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
- Understand all the potential areas where untrusted inputs can enter the product, including but not limited to: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in Foxit PDF Editor
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 8.1 High severity
- 7.8 High severity
- 7.8 High severity
Recent Improper Input Validation vulnerabilities
- 7.1 High severity
- 7.2 High severity
- 8.8 High severity
- 9.8 Critical severity
- 9.6 Critical severity
- 7.8 High severity
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