Kernel compromise via stale replay response double-free
Published Jul 25, 2026 · Updated Jul 25, 2026
Double-free in the Linux Kernel SMB client allows remote attackers controlling an SMB server to crash or compromise the kernel. SMB2_ioctl() frees a response after a replayable error, but an initialization failure leaves the prior buffer type set so cleanup releases the same buffer again. Exploitation requires an existing SMB3 mount to a malicious or compromised server; the resulting heap corruption supports a kernel panic, memory disclosure, arbitrary writes, or control-flow hijacking.
Summary
What happened
Double-free in the Linux Kernel SMB client allows remote attackers controlling an SMB server to crash or compromise the kernel. SMB2_ioctl() frees a response after a replayable error, but an initialization failure leaves the prior buffer type set so cleanup releases the same buffer again. Exploitation requires an existing SMB3 mount to a malicious or compromised server; the resulting heap corruption supports a kernel panic, memory disclosure, arbitrary writes, or control-flow hijacking.
The record
- CVE
- CVE-2026-64385
- Published
- Jul 25, 2026
- Updated
- Jul 25, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- CWE-1341, T1203
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 25, 2026CVE publishedPublication date reported by the CVE source.
- Jul 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=433042a91f9373241307725b52de573933ffedbf <0be4bc64882edaefaaee8d1e27d083643eb778e6
- Affected versionversion=4f1fffa2376922f3d1d506e49c0fd445b023a28e <276c8efbc49f9303ac76d0d4deab7128581b0f3b
- Affected versionversion=4f1fffa2376922f3d1d506e49c0fd445b023a28e <96fcfc8ae7359346156e492ca610e830d2649ad6
- Affected versionversion=4f1fffa2376922f3d1d506e49c0fd445b023a28e <f9bbadb6c94583e3b4af1afc449bfceb1d1ddec9
- Affected versionversion=4f1fffa2376922f3d1d506e49c0fd445b023a28e <fc65ffb4ef1bf540da16b17c225ae51091e07d72
- Affected versionversion=6.6.32 <6.6.145
- Affected versionversion=6.8
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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