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NVD / CVE Program· CNA Linux

CVE-2023-52479: ksmbd: fix uaf in smb20_oplock_break_ack

Noroxi assessment

Priority: Monitor (action score 35/100)

  • 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: 0.60% (FIRST EPSS).
  • Anyone who can reach it over the internet 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 694e13732e830cbbfedb562e57f28644927c33fd, 8226ffc759ea59f10067b9acdf7f94bae1c69930, c69813471a1ec081a0b9bf0c6bd7e8afd818afce.

Low priority for now. Upgrade to Linux Linux 694e13732e830cbbfedb562e57f28644927c33fd, 8226ffc759ea59f10067b9acdf7f94bae1c69930, c69813471a1ec081a0b9bf0c6bd7e8afd818afce 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 uaf in smb20_oplock_break_ack drop reference after use opinfo.

HighCVSS 8.8 · v3.1—No exploit Fix available
Published
Feb 29, 2024
Updated
Aug 15, 2026
EPSS
0.6% · 49th percentile

Report tools

JSON

Action score

35

Monitor

Low priority for now.

CVSS
35 / 40 · 8.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.6%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
8.8
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-2023-52479

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 kernelbefore 5.15.135
  • linux linux kernel5.16 and later · before 6.1.57
  • linux linux kernel6.2 and later · before 6.5.7
  • linux linux kernel6.6

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

    • 5.15affected
    • e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and later · before 694e13732e830cbbfedb562e57f28644927c33fdaffected · git
    • e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and later · before 8226ffc759ea59f10067b9acdf7f94bae1c69930affected · git
    • e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and later · before d5b0e9d3563e7e314a850e81f42b2ef6f39882f9affected · git
    • e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and later · before c69813471a1ec081a0b9bf0c6bd7e8afd818afceaffected · git
    • before 5.15not affected · semver
    • 5.15.135 and later · up to and including 5.15.*not affected · semver
    • 6.1.57 and later · up to and including 6.1.*not affected · semver
    • 6.5.7 and later · up to and including 6.5.*not affected · semver
    • 6.6 and laternot affected · original_commit_for_fix

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.64-16.1.64-1
Debian:13linuxbefore 6.5.8-16.5.8-1

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-2023-52477Feb 29, 2024 · usb: hub: Guard against accesses to uninitialized BOS descriptors
    22Monitor
  • ← EarlierCVE-2023-52478Feb 29, 2024 · HID: logitech-hidpp: Fix kernel crash on receiver USB disconnect
    18Monitor
  • Later →CVE-2023-52480Feb 29, 2024 · ksmbd: fix race condition between session lookup and expire
    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 Linux694e13732e830cbbfedb562e57f28644927c33fdVendor (CNA)
Linux Linux8226ffc759ea59f10067b9acdf7f94bae1c69930Vendor (CNA)
Linux Linuxc69813471a1ec081a0b9bf0c6bd7e8afd818afceVendor (CNA)
Linux Linuxd5b0e9d3563e7e314a850e81f42b2ef6f39882f9Vendor (CNA)
debian:linux6.1.64-1 · Debian:12Package 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.

No nightly-computed relations.

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.
  • 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
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

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

nvd-secondary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

c
free(dev->buf);/* ... another thread is still running ... */process(dev->buf);

Fixed

c
lock(&dev->lock);free(dev->buf);dev->buf = NULL;unlock(&dev->lock);

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 (3 more)

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

All records