CVE-2025-21947: ksmbd: fix type confusion via race condition when using ipc_msg_send_request

mediumCVSS 4.7CVE-2025-21947

CSIRTS triage

vendor: Linux product: Linux kernel Memory corruption Privilege escalation

What: Type confusion via race condition in ksmbd IPC message handling can corrupt kernel memory.
Who is affected: Systems running ksmbd kernel SMB server with concurrent IPC message processing.
Urgency: Medium; requires race condition exploitation and affects SMB server implementations.
Action: Update to a patched Linux kernel version with ksmbd IPC race condition fixes.

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: 2026-08-06
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21947

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-2025-219470.36% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 29% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2025-21947	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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

high[UPDATE] [high] Linux Kernel: Multiple vulnerabilitiescert-bund

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-2026-64392: ksmbd: use opener credentials for delete-on-closemsrc · 2026-08-06
mediumCVE-2024-50284: ksmbd: Fix the missing xa_store error checkmsrc · 2026-08-06
mediumCVE-2025-71150: ksmbd: Fix refcount leak when invalid session is found on session lookupmsrc · 2026-08-06
highCVE-2026-64395: ksmbd: require source read access for duplicate extentsmsrc · 2026-08-06
mediumCVE-2026-64397: ksmbd: serialize QUERY_DIRECTORY requests per filemsrc · 2026-08-06
mediumCVE-2026-64400: ksmbd: prevent path traversal bypass by restricting caseless retrymsrc · 2026-08-06