Kernel-level vulnerability in the Linux SMB client affecting widely deployed OSes; can disrupt systems and requires org-wide attention.
CVE-2026-64387
Linux kernel SMB client double-free leading to kernel memory corruption and remote DoS/escalation.
Is CVE-2026-64387 being exploited?
Not confirmed. CVE-2026-64387 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.46% probability of exploitation in the next 30 days.
How severe is CVE-2026-64387?
CVE-2026-64387 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-64387?
Yes. A fix has been recorded for CVE-2026-64387. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-64387 affect?
CVE-2026-64387 affects Linux kernel (SMB/CIFS client), Any distro using vulnerable kernel SMB code. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-64387?
Apply vendor kernel/security updates immediately; restrict/block untrusted SMB servers.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
A malicious SMB server can trigger a double-free in the kernel SMB client, causing kernel memory corruption, remote crash (DoS) or possible privilege escalation.
Immediate action required
- affected>= 433042a91f9373241307725b52de573933ffedbf and < 3409aedf3c81a810243da94164f6621c9d205c98
- affected>= 4f1fffa2376922f3d1d506e49c0fd445b023a28e and < 1665f25b1dea30bf2d02e16245d203a944c9d994
- affected>= 4f1fffa2376922f3d1d506e49c0fd445b023a28e and < 00b0fa425941438b664950a8ee65dfba2def4336
- affected>= 4f1fffa2376922f3d1d506e49c0fd445b023a28e and < 3317a5d015fca976475aa71df224056777316fde
- affected>= 4f1fffa2376922f3d1d506e49c0fd445b023a28e and < 9647492b5e41954be59d5157eddbcd4cdc1656f7
- affected>= 6.6.32 and < 6.6.145
- affected6.8
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.