Skip to content
Noroxi
NVD / CVE Program· CNA Linux

CVE-2026-64384: smb: client: fix change notify replay double-free

Noroxi assessment

Priority: Monitor (action score 39/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.45% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: Linux Linux 145f820dcbb2cced374f2532f8a61a44dce4a615, 52af1975f0dfae990c5a0e85872cc41be0e88a68, 5821f9dbb8b5b24391850a13418e633edd0fb003; azl3 kernel 6.6.144.1-1 on Azure Linux 3.0 6.6.145.2-1.

Low priority for now. Upgrade to Linux Linux 145f820dcbb2cced374f2532f8a61a44dce4a615, 52af1975f0dfae990c5a0e85872cc41be0e88a68, 5821f9dbb8b5b24391850a13418e633edd0fb003; azl3 kernel 6.6.144.1-1 on Azure Linux 3.0 6.6.145.2-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix change notify replay double-free A response-bearing attempt can return a replayable error and free its response buffer. If SMB2_notify_init() fails before the next send, cleanup retains the previous buffer type and frees that response again. Reset response bookkeeping before each attempt to prevent the stale free.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Jul 25, 2026
Updated
Oct 19, 2026
EPSS
0.4% · 39th percentile

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
9.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-64384

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits instantly.

Your free account also gets you

Running WordPress? Scan your site free with WP Lens

  • Stack alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for linux records

Running WordPress? Scan your site free with WP Lens

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

We use this product, ask for help

Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel6.6.32 and later · before 6.6.145
  • linux linux kernel6.8.1 and later · before 6.12.96
  • linux linux kernel6.13 and later · before 6.18.39
  • linux linux kernel6.19 and later · before 7.1.4
  • linux linux kernel6.8

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 6.8affected
    • 433042a91f9373241307725b52de573933ffedbf and later · before 5821f9dbb8b5b24391850a13418e633edd0fb003affected · git
    • 4f1fffa2376922f3d1d506e49c0fd445b023a28e and later · before d684f4134998085702009b94c35c2003fc9e72d3affected · git
    • 4f1fffa2376922f3d1d506e49c0fd445b023a28e and later · before 52af1975f0dfae990c5a0e85872cc41be0e88a68affected · git
    • 4f1fffa2376922f3d1d506e49c0fd445b023a28e and later · before 901891513951bc8322ece754863909ea45af95c6affected · git
    • 4f1fffa2376922f3d1d506e49c0fd445b023a28e and later · before 145f820dcbb2cced374f2532f8a61a44dce4a615affected · git
    • 6.6.32 and later · before 6.6.145affected · semver
    • before 6.8not affected · semver
    • 6.6.145 and later · up to and including 6.6.*not affected · semver
    • 6.12.96 and later · up to and including 6.12.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:9kernelbefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-64kbefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-64k-corebefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-64k-debugbefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-64k-debug-corebefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-64k-debug-develbefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-64k-debug-devel-matchedbefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-64k-debug-modulesbefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-64k-debug-modules-corebefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-64k-debug-modules-extrabefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-64k-develbefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-64k-devel-matchedbefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-64k-modulesbefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-64k-modules-corebefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-64k-modules-extrabefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-abi-stablelistsbefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-corebefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-cross-headersbefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-debugbefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-debug-corebefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-debug-develbefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-debug-devel-matchedbefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-debug-modulesbefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8
AlmaLinux:9kernel-debug-modules-corebefore 5.14.0-687.45.1.el9_85.14.0-687.45.1.el9_8

+96

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-64382Jul 25, 2026 · smb: client: fix double-free in SMB2_open() replay
    35Monitor
  • ← EarlierCVE-2026-64383Jul 25, 2026 · smb: client: fix double-free in SMB2_flush() replay
    39Monitor
  • Later →CVE-2026-64385Jul 25, 2026 · smb: client: fix double-free in SMB2_ioctl() replay
    39Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux145f820dcbb2cced374f2532f8a61a44dce4a615Vendor (CNA)
Linux Linux52af1975f0dfae990c5a0e85872cc41be0e88a68Vendor (CNA)
Linux Linux5821f9dbb8b5b24391850a13418e633edd0fb003Vendor (CNA)
Linux Linux6.6.145Vendor (CNA)
Linux Linux901891513951bc8322ece754863909ea45af95c6Vendor (CNA)
Linux Linuxd684f4134998085702009b94c35c2003fc9e72d3Vendor (CNA)
azl3 kernel 6.6.144.1-1 on Azure Linux 3.06.6.145.2-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
almalinux:kernel5.14.0-687.45.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k5.14.0-687.45.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-core5.14.0-687.45.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug5.14.0-687.45.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-core5.14.0-687.45.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel5.14.0-687.45.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched5.14.0-687.45.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules5.14.0-687.45.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-core5.14.0-687.45.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra5.14.0-687.45.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel5.14.0-687.45.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel-matched5.14.0-687.45.1.el9_8 · AlmaLinux:9Package registry (OSV)
debian:linux6.12.96-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.100-1~deb12u1 · Debian:12Package registry (OSV)
red hat:kernel-64k-debug-debuginfo0:5.14.0-687.45.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debug-devel0:5.14.0-687.45.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debug-devel-matched0:5.14.0-687.45.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debuginfo0:5.14.0-687.45.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-devel0:5.14.0-687.45.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-devel-matched0:5.14.0-687.45.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debug-debuginfo0:5.14.0-687.45.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debug-devel0:5.14.0-687.45.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-debug-devel-matched0:5.14.0-687.45.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)

+4

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-643830 days apartsmb: client: fix double-free in SMB2_flush() replay
    39Monitor
  • CVE-2026-643850 days apartsmb: client: fix double-free in SMB2_ioctl() replay
    39Monitor
  • CVE-2026-643860 days apartsmb: client: fix query_info() replay double-free
    39Monitor
  • CVE-2026-643870 days apartsmb: client: fix query directory replay double-free
    39Monitor
  • CVE-2026-638886 days apartscsi: target: iscsi: Fix CRC overread and double-free in iscsit_handle_text_cmd()
    39Monitor
  • CVE-2026-5299331 days aparttipc: fix double-free in tipc_buf_append()
    39Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-415 · Double Free

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (4 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records