CVE-2026-53198: ksmbd: fix use-after-free of a deferred file_lock on double SMB2_CANCEL

highCVSS 7.8CVE-2026-53198

CSIRTS triage

product: ksmbd Memory corruption

What: This vulnerability involves a use-after-free issue related to a deferred file lock on double SMB2_CANCEL.
Who is affected: Deployments using ksmbd are at risk.
Urgency: Remediation is high priority due to a severity rating of 7.8.
Action: Apply the fix for CVE-2026-53198.

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: high — CVSS 7.8
Published: 2026-06-09
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-53198

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-2026-531980.47% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 37% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-53198	coverage & exploitation status	NVD · CVE.org

Recent advisories for ksmbd

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-2026-52996: ksmbd: fix durable fd leak on ClientGUID mismatch in durable v2 openmsrc · 2026-06-09
highCVE-2026-52911: ksmbd: scope conn->binding slowpath to bound sessions onlymsrc · 2026-06-09
criticalCVE-2026-53010: ksmbd: fix use-after-free in smb2_open during durable reconnectmsrc · 2026-06-09
mediumCVE-2026-53046: ksmbd: fix use-after-free from async crypto on Qualcomm crypto enginemsrc · 2026-06-09
criticalCVE-2026-52944: ksmbd: fix FSCTL permission bypass by adding a permission check for FSCTL_SET_SPARSEmsrc · 2026-06-09