CVE-2026-68448: ovl: check access to copy_file_range source with src mounter creds

mediumCVSS 4.7CVE-2026-68448

CSIRTS triage

vendor: Linux product: Linux Kernel Privilege escalation

What: The overlay filesystem does not properly check access permissions on copy_file_range source with source mounter credentials.
Who is affected: Systems using Linux overlay filesystem for container or multi-user deployments.
Urgency: Medium priority; privilege escalation via filesystem operation bypass.
Action: Apply Linux kernel patch to validate source mounter credentials in copy_file_range.

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 4.7
Published: 2026-08-11
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-68448

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-2026-684480.15% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 5% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-68448	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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Recent advisories for ovl

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.

unknownCVE-2026-74619: In the Linux kernel, the following vulnerability has been resolved: ovl: don't warn when the m…nvd · 2026-08-22
unknownCVE-2026-68448: In the Linux kernel, the following vulnerability has been resolved: ovl: check access to copy_…nvd · 2026-08-12
mediumCVE-2026-74619: ovl: don't warn when the mount is completed from another user namespacemsrc · 2026-08-11