CVE-2026-5426

CVE Enrichment

CVSS: 9.1 CRITICAL
EPSS: 1.01%
EPSS Percentile: 63.07%
CISA KEV: Not listed

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

Technical Details

CVSS Version: 3.1
CNA / NVD Source: [email protected]
Published: 16-Apr-2026 23:16
Last Modified: 27-Oct-2026 04:10
EPSS Date: 2026-11-01
CWE: CWE-321, CWE-502

CVSS Vector


            CVSS:3.1                            AV:N /
                            AC:L /
                            PR:N /
                            UI:N /
                            S:U /
                            C:H /
                            I:H /
                            A:N

References

Last enrichment sync: 02-Nov-2026 20:49
Sources: NVD · FIRST EPSS · CISA KEV
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Reported Context (2)

Mandiant reported that attackers exploited CVE-2026-5426 in KnowledgeDeliver LMS servers as a zero-day to deploy the Godzilla web shell and gain remote code execution through ViewState deserialization. KnowledgeDeliver flaw exploited as zero-day to deploy web shells
Mandiant investigated a compromise of KnowledgeDeliver, a Japanese LMS from Digital Knowledge, caused by a shared ASP.NET machine key weakness that enabled unauthenticated RCE and was tracked as CVE-2026-5426. Mandiant Details KnowledgeDeliver Exploitation via Shared ASP.NET Machine Keys

Malware (3)

MITRE ATT&CK (8)

Vendors (2)

Products (3)

Tools (1)

Countries (1)

Note: Related entities, including threat actors, malware, CVEs, MITRE ATT&CK techniques, vendors, products, tools, countries, and industries, are shown when they appear in the same reporting. Their presence does not necessarily mean they were targeted, compromised, vulnerable, responsible for the activity, or directly involved in the incident.