How severe is CVE-2026-5426?

CVE-2026-5426 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-5426 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-5426?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-5426 have an EU (EUVD) identifier?

Yes. CVE-2026-5426 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23271.

When was CVE-2026-5426 published?

CVE-2026-5426 was published on 2026-04-16 and last updated on 2026-06-17.

CVE-2026-5426

CVE-2026-5426 is a critical-severity vulnerability with a CVSS 3.x base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-321.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
EPSS exploit prediction: 1% (59th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-23271
Weakness: CWE-321
Published: 2026-04-16
Last modified: 2026-06-17

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

Frequently asked questions

What is CVE-2026-5426?: 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
How severe is CVE-2026-5426?: CVE-2026-5426 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-5426 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-5426?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-5426 have an EU (EUVD) identifier?: Yes. CVE-2026-5426 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23271.
When was CVE-2026-5426 published?: CVE-2026-5426 was published on 2026-04-16 and last updated on 2026-06-17.

References

Other CWE-321 vulnerabilities

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