CVE-2026-74595: fscrypt: use the mount idmap for the owner check in fscrypt_ioctl_set_policy()

mediumCVSS 6.1CVE-2026-74595

CSIRTS triage

vendor: Linux product: Linux Privilege escalation

What: fscrypt owner check does not properly use the mount idmap, allowing privilege escalation.
Who is affected: Linux systems with fscrypt enabled and user namespaces in use.
Urgency: Moderate; CVSS 6.1 and privilege escalation capability warrant prompt patching.
Action: Apply kernel patch or upgrade to a Linux version with the fscrypt idmap fix.

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 6.1
Published: 2026-08-11
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-74595

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-2026-745950.09% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 1% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-74595	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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

Recent advisories for fscrypt

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.

highCVE-2026-74595: In the Linux kernel, the following vulnerability has been resolved: fscrypt: use the mount idm…nvd · 2026-08-22
mediumCVE-2026-68147: fscrypt: Avoid dynamic allocation in fscrypt_get_devices()msrc · 2026-08-11
mediumCVE-2026-68148: fscrypt: Add missing superblock check in find_or_insert_direct_key()msrc · 2026-08-11
highCVE-2026-68148: In the Linux kernel, the following vulnerability has been resolved: fscrypt: Add missing super…nvd · 2026-08-10
highCVE-2026-68147: In the Linux kernel, the following vulnerability has been resolved: fscrypt: Avoid dynamic all…nvd · 2026-08-10