CVE-2026-58638: Windows Boot Loader Security Feature Bypass Vulnerability

mediumCVSS 6CVE-2026-58638

Missing cryptographic step in Windows Boot Loader allows an authorized attacker to bypass a security feature locally.

CSIRTS triage

vendor: Microsoft product: WindowsOther

What: Missing cryptographic step in Windows Boot Loader allows an authorized attacker to bypass a security feature locally.
Who is affected: Authorized users of Windows Boot Loader are affected.
Urgency: Remediation is important due to the medium severity and potential for security feature bypass.
Action: Apply the latest security update for Windows Boot Loader.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: medium — CVSS 6
Published: 2026-07-14
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-58638

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-586380.23% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 14% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-58638	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

mediumCVE-2026-58638: Missing cryptographic step in Windows Boot Loader allows an authorized attacker to bypass a se…nvd
unknownexploitedNCSC-2026-0231 [1.00] [M/H] Vulnerabilities fixed in Microsoft Windowsncsc-nl

Recent advisories for Windows Boot Loader

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

mediumCVE-2026-58638: Missing cryptographic step in Windows Boot Loader allows an authorized attacker to bypass a se…nvd · 2026-07-14