CVE-2026-64578: ksmbd: validate compound request size before reading StructureSize2

mediumCVSS 6.5CVE-2026-64578

Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: medium — CVSS 6.5
Published: 2026-08-06
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-64578

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-2026-645780.16% 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-2026-64578	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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

medium[UPDATE] [medium] Linux Kernel: Multiple vulnerabilitiescert-bund
unknownDSA-6415-1 linux - security updatedebian
highCVE-2026-64578: In the Linux kernel, the following vulnerability has been resolved: ksmbd: validate compound r…nvd

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.

mediumCVE-2026-64390: ksmbd: track the connection owning a byte-range lockmsrc · 2026-08-06
highCVE-2026-64392: ksmbd: use opener credentials for delete-on-closemsrc · 2026-08-06
highCVE-2025-40039: ksmbd: Fix race condition in RPC handle list accessmsrc · 2026-08-06
unknownCVE-2024-49988: ksmbd: add refcnt to ksmbd_conn structmsrc · 2026-08-06
highCVE-2026-64395: ksmbd: require source read access for duplicate extentsmsrc · 2026-08-06
mediumCVE-2025-21947: ksmbd: fix type confusion via race condition when using ipc_msg_send_requestmsrc · 2026-08-06