CVE-2026-64380

highCVSS 8.2covered by 2 sourcesfirst seen 2026-07-14

In the Linux kernel, the following vulnerability has been resolved: smb: client: harden POSIX SID length parsing posix_info_sid_size() reads sid[1] to obtain the subauthority count, but its existing boundary check still accepts buffers with only one remaining byte. Require two bytes before reading sid[1] so all client paths that reuse the helper reject truncated POSIX SIDs safely.

CSIRTS triage

What: The smb client has been hardened against POSIX SID length parsing issues.
Who is affected: Deployments of the smb client are affected.
Urgency: Remediation is necessary to prevent potential exploitation, although exploitation status is currently unknown.
Action: Update to the latest version of the smb client.

AI-assisted analysis generated from the source advisory — verify against the original.

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Exploitation outlook

Low exploitation risk0.44% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 36% of all EPSS-scored CVEs.

Advisory coverage (2)

highCVE-2026-64380: In the Linux kernel, the following vulnerability has been resolved: smb: client: harden POSIX …nvd · 2026-07-25
highCVE-2026-64380: smb: client: harden POSIX SID length parsingmsrc · 2026-07-14

External references

NVD record for CVE-2026-64380

CVE.org record

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