smb: client: fix double-free in SMB2_flush() replay (CVE-2026-64383) | HOL Guard CVE

Critical · CVSS 9.8CVE-2026-64383

smb: client: fix double-free in SMB2_flush() replay

Answer in brief

CVE-2026-64383 records a Critical severity (CVSS 9.8) vulnerability in smb: client: fix double-free in SMB2_flush() replay. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Jul 25, 2026Updated Sep 4, 2026Source checked Sep 20, 2026First seen by HOL Aug 5, 2026Material review Sep 4, 2026

Upstream Advisory

Key facts

Risk: Critical · CVSS 9.8
Exploitation: Not marked as known exploited
Affected software: 10 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 9.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Affected products and reported versions
Product	Affected versions	Fixed versions
cpe:2.3:o:linux:linux_kernel::::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:6.8:-::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:6.8:rc2::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:6.8:rc3::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:6.8:rc4::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:6.8:rc5::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:6.8:rc6::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:6.8:rc7::::::	Not reported	Not reported

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=433042a91f9373241307725b52de573933ffedbf <6e27f40b682a5e42a2daae3ce6d96f0e0e16dedb \|\| >=4f1fffa2376922f3d1d506e49c0fd445b023a28e <878757163eea684750107a31ea134c103863515d \|\| >=4f1fffa2376922f3d1d506e49c0fd445b023a28e <3407240cde132a4b72d6429a2625a09a2f78adaf \|\| >=4f1fffa2376922f3d1d506e49c0fd445b023a28e <013a9a3da46c5dabcf18f65ea6a47874ba12a15d \|\| >=4f1fffa2376922f3d1d506e49c0fd445b023a28e <4be31c943a3a27a5a0251dbb8f5cb89059ec3d5a \|\| >=6.6.32 <6.6.145	6e27f40b682a5e42a2daae3ce6d96f0e0e16dedb, 878757163eea684750107a31ea134c103863515d, 3407240cde132a4b72d6429a2625a09a2f78adaf, 013a9a3da46c5dabcf18f65ea6a47874ba12a15d, 4be31c943a3a27a5a0251dbb8f5cb89059ec3d5a, 6.6.145
Linux/Linuxgeneric	6.8	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 6e27f40b682a5e42a2daae3ce6d96f0e0e16dedb if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Jul 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 4, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 5, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix double-free in SMB2_flush() replay SMB2_flush() keeps its response buffer bookkeeping across replay attempts. If a replayable flush response is received and the retry then fails before cifs_send_recv() stores a replacement response, flush_exit will free the stale response pointer a second time. Reinitialize resp_buftype and rsp_iov at the top of the replay loop so cleanup only acts on response state produced by the current attempt. This fixes a double-free without changing replay handling for successful requests.

Quoted source text, attributed separately from HOL analysis.