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NVD / CVE Program· CNA Linux

CVE-2026-46139: smb: client: use kzalloc to zero-initialize security descriptor buffer

Noroxi assessment

Priority: Monitor (action score 22/100)

  • 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: 0.12% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 4c3ed344a970aad51388ac3b0145b98318f0e21f, 5e489c6c47a2ac15edbaca153b9348e42c1eacab, 6.12.88.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 4c3ed344a970aad51388ac3b0145b98318f0e21f, 5e489c6c47a2ac15edbaca153b9348e42c1eacab, 6.12.88 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: use kzalloc to zero-initialize security descriptor buffer Commit 62e7dd0a39c2d ("smb: common: change the data type of num_aces to le16") split struct smb_acl's __le32 num_aces field into __le16 num_aces and __le16 reserved. The reserved field corresponds to Sbz2 in the MS-DTYP ACL wire format, which must be zero [1]. When building an ACL descriptor in build_sec_desc(), we are using a kmalloc()'ed descriptor buffer and writing the fields explicitly using le16() writes now. This never writes to the 2 byte reserved field, leaving it as uninitialized heap data. When the reserved field happens to contain non-zero slab garbage, Samba rejects the security descriptor with "ndr_pull_security_descriptor failed: Range Error", causing chmod to fail with EINVAL. Change kmalloc() to kzalloc() to ensure the entire buffer is zero-initialized. [1] https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-dtyp/20233ed8-a6c6-4097-aafa-dd545ed24428

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
May 28, 2026
Updated
Jun 24, 2026
EPSS
0.1% · 1th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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

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  • when it enters CISA KEV
  • when exploit code appears or is weaponized
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  • when EPSS rises 20 points in a week

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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.

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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 kernel6.12.23 and later · before 6.12.88
  • linux linux kernel6.13.11 and later · before 6.14
  • linux linux kernel6.14.1 and later · before 6.18.30
  • linux linux kernel6.19 and later · before 7.0.7
  • linux linux kernel6.14
  • linux linux kernel7.1

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

    • 191f2f444745087c3c51fd6042a0e25f42315ab0, 6.14affected
    • 1593ddb37bd124c131fe635397df68e854a03108 and later · before 4c3ed344a970aad51388ac3b0145b98318f0e21faffected · git
    • da087905e3270e2291c0afae39a28e7d183e5ec3 and later · before 941a1e6eb35440336913afc88a82103291956d5daffected · git
    • 62e7dd0a39c2d0d7ff03274c36df971f1b3d2d0d and later · before be1ef9512a3f5a755895c24f31b334342f4aa15baffected · git
    • 62e7dd0a39c2d0d7ff03274c36df971f1b3d2d0d and later · before 9bdb2ca31368b7671949dfb94a5d57ffccd01eddaffected · git
    • 62e7dd0a39c2d0d7ff03274c36df971f1b3d2d0d and later · before 5e489c6c47a2ac15edbaca153b9348e42c1eacabaffected · git
    • 6.12.23 and later · before 6.12.88affected · semver
    • 6.13.11 and later · before 6.14affected · semver
    • before 6.14not affected · semver
    • 6.12.88 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
Debian:13linuxbefore 6.12.88-16.12.88-1
Debian:14linuxbefore 7.0.7-17.0.7-1

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-2026-46131May 28, 2026 · KVM: x86: check for nEPT/nNPT in slow flush hypercalls
    22Monitor
  • ← EarlierCVE-2026-46134May 28, 2026 · platform/chrome: cros_ec_typec: Init mutex in Thunderbolt registration
    22Monitor
  • Later →CVE-2026-46140May 28, 2026 · Bluetooth: btmtk: validate WMT event SKB length before struct access
    28Monitor

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 Linux4c3ed344a970aad51388ac3b0145b98318f0e21fVendor (CNA)
Linux Linux5e489c6c47a2ac15edbaca153b9348e42c1eacabVendor (CNA)
Linux Linux6.12.88Vendor (CNA)
Linux Linux6.14Vendor (CNA)
Linux Linux941a1e6eb35440336913afc88a82103291956d5dVendor (CNA)
Linux Linux9bdb2ca31368b7671949dfb94a5d57ffccd01eddVendor (CNA)
Linux Linuxbe1ef9512a3f5a755895c24f31b334342f4aa15bVendor (CNA)
debian:linux6.12.88-1 · Debian:13Package registry (OSV)

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.

No history yet (it accumulates with the daily EPSS job).

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-2026-5298927 days apartnvmet-tcp: propagate nvmet_tcp_build_pdu_iovec() errors to its callers
    39Monitor
  • CVE-2026-5322528 days apartsctp: fix uninit-value in __sctp_rcv_asconf_lookup()
    36Monitor
  • CVE-2026-5317028 days apartaccel/ethosu: reject DMA commands with uninitialized length
    35Monitor
  • CVE-2026-4313922 days apartxfrm6: fix uninitialized saddr in xfrm6_get_saddr()
    34Monitor
  • CVE-2026-4329120 days apartnet: nfc: nci: Fix parameter validation for packet data
    33Monitor
  • CVE-2026-4345620 days apartbonding: fix type confusion in bond_setup_by_slave()
    31Monitor

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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-908 · Use of Uninitialized Resource

CVSS vector

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

nvd-primary

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. 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