Linux kernel is core OS used widely; an SMB client kernel bug can affect many servers/desktops and enable crashes or kernel compromise, requiring org-wide action.
CVE-2026-64383
Linux kernel SMB client double-free -> kernel memory corruption, potential RCE or DoS
Is CVE-2026-64383 being exploited?
Not confirmed. CVE-2026-64383 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-2026-64383?
CVE-2026-64383 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-2026-64383?
Yes. A fix has been recorded for CVE-2026-64383. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-64383 affect?
CVE-2026-64383 affects Linux kernel (CIFS/SMB client), Systems mounting SMB shares, Desktops/servers using SMB client stacks. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-64383?
Apply kernel security updates immediately; block untrusted SMB servers; restrict SMB client access via firewall.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Heap double-free in SMB2_flush replay allows a remote (malicious SMB server) to trigger kernel memory corruption, causing DoS or possible privilege escalation/RCE.
Immediate action required
- affected>= 433042a91f9373241307725b52de573933ffedbf and < 6e27f40b682a5e42a2daae3ce6d96f0e0e16dedb
- affected>= 4f1fffa2376922f3d1d506e49c0fd445b023a28e and < 878757163eea684750107a31ea134c103863515d
- affected>= 4f1fffa2376922f3d1d506e49c0fd445b023a28e and < 3407240cde132a4b72d6429a2625a09a2f78adaf
- affected>= 4f1fffa2376922f3d1d506e49c0fd445b023a28e and < 013a9a3da46c5dabcf18f65ea6a47874ba12a15d
- affected>= 4f1fffa2376922f3d1d506e49c0fd445b023a28e and < 4be31c943a3a27a5a0251dbb8f5cb89059ec3d5a
- 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.