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NVD / CVE Program· CNA Linux

CVE-2023-52440: ksmbd: fix slub overflow in ksmbd_decode_ntlmssp_auth_blob()

Noroxi assessment

Priority: Monitor (action score 38/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 22.3% (FIRST EPSS); higher than 97.7% of all records.
  • 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 30fd6521b2fbd9b767e438e31945e5ea3e3a2fba, 4b081ce0d830b684fdf967abc3696d1261387254, 7f1d6cb0eb6af3a8088dc24b7ddee9a9711538c4.
  • Severity is disputed: the assigning authority (CNA) scores it 9.8, NVD 7.8.

Low priority for now. Upgrade to Linux Linux 30fd6521b2fbd9b767e438e31945e5ea3e3a2fba, 4b081ce0d830b684fdf967abc3696d1261387254, 7f1d6cb0eb6af3a8088dc24b7ddee9a9711538c4 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: ksmbd: fix slub overflow in ksmbd_decode_ntlmssp_auth_blob() If authblob->SessionKey.Length is bigger than session key size(CIFS_KEY_SIZE), slub overflow can happen in key exchange codes. cifs_arc4_crypt copy to session key array from SessionKey from client.

HighCVSS 7.8 · v3.1—Proof of concept Fix available
Published
Feb 21, 2024
Updated
Aug 15, 2026
EPSS
22.3% · 97th percentile

Report tools

JSON

Action score

38

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
7 / 30 · 22.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
7.8
CNA · Linux
9.8
2.0 point gap

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

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
  • Proof of concept exists, no weaponized module
  • A fix has been released

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

Follow CVE-2023-52440

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

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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 kernel5.17.0 and later · before 6.1.52
  • linux linux kernel6.2.0 and later · before 6.4.15
  • linux linux kernel6.5.0 and later · before 6.5.2

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

    • 5.17affected
    • c5049d2d73b2dc8e6bb64be633250bad1ae3d9ef and later · before bd554ed4fdc3d38404a1c43d428432577573e809affected · git
    • f9929ef6a2a55f03aac61248c6a3a987b8546f2a and later · before 30fd6521b2fbd9b767e438e31945e5ea3e3a2fbaaffected · git
    • f9929ef6a2a55f03aac61248c6a3a987b8546f2a and later · before 7f1d6cb0eb6af3a8088dc24b7ddee9a9711538c4affected · git
    • f9929ef6a2a55f03aac61248c6a3a987b8546f2a and later · before ecd7e1c562cb08e41957fcd4b0e404de5ab38e20affected · git
    • f9929ef6a2a55f03aac61248c6a3a987b8546f2a and later · before 4b081ce0d830b684fdf967abc3696d1261387254affected · git
    • before 5.17not affected · semver
    • 6.1.52 and later · up to and including 6.1.*not affected · semver
    • 6.4.15 and later · up to and including 6.4.*not affected · semver
    • 6.5.2 and later · up to and including 6.5.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.52-16.1.52-1
Debian:13linuxbefore 6.5.3-16.5.3-1

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-2023-52438Feb 20, 2024 · binder: fix use-after-free in shinker's callback
    31Monitor
  • ← EarlierCVE-2023-52439Feb 20, 2024 · uio: Fix use-after-free in uio_open
    31Monitor
  • Later →CVE-2023-52441Feb 21, 2024 · ksmbd: fix out of bounds in init_smb2_rsp_hdr()
    31Monitor

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 Linux30fd6521b2fbd9b767e438e31945e5ea3e3a2fbaVendor (CNA)
Linux Linux4b081ce0d830b684fdf967abc3696d1261387254Vendor (CNA)
Linux Linux7f1d6cb0eb6af3a8088dc24b7ddee9a9711538c4Vendor (CNA)
Linux Linuxbd554ed4fdc3d38404a1c43d428432577573e809Vendor (CNA)
Linux Linuxecd7e1c562cb08e41957fcd4b0e404de5ab38e20Vendor (CNA)
debian:linux6.1.52-1 · Debian:12Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:542025-09-12

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.

  1. Published
  2. First PoC+569 d
  3. TodayNov 10, 2026+993 d
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-2021-4734890 days apartdrm/amd/display: Avoid HDCP over-read and corruption
    36Monitor
  • CVE-2022-3640488 days apartLinux Kernel Bluetooth l2cap_core.c l2cap_conn_del use after free
    35Monitor
  • CVE-2023-524341 days apartsmb: client: fix potential OOBs in smb2_parse_contexts()
    32Monitor
  • CVE-2023-524410 days apartksmbd: fix out of bounds in init_smb2_rsp_hdr()
    31Monitor
  • CVE-2024-265881 days apartLoongArch: BPF: Prevent out-of-bounds memory access
    31Monitor
  • CVE-2024-265891 days apartbpf: Reject variable offset alu on PTR_TO_FLOW_KEYS
    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).

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

Weakness class (CWE)

CWE-119 · Improper Restriction of Operations within the Bounds of a Memory Buffer

CVSS vector

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

ATT&CK techniques

—

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