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NVD / CVE Program· CNA Linux

CVE-2026-90153: ksmbd: bound smb_check_perm_dacl() ACE walks by DACL size

Noroxi assessment

Priority: Monitor (action score 32/100)

  • 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: 0.47% (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 5.16, 5.19, 5.20.

Low priority for now. Upgrade to Linux Linux 5.16, 5.19, 5.20 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: bound smb_check_perm_dacl() ACE walks by DACL size smb_check_perm_dacl() validates that the DACL fits inside the NT security descriptor, but then bounds its two ACE walks by the remaining NTSD length (acl_size) rather than the DACL's declared size (pdacl_size). When pdacl->size is smaller than the trailing NTSD buffer, bytes after the declared DACL boundary - still inside the stored security descriptor - are parsed as ACEs during access checks. A crafted DACL can place an access-granting ACE beyond pdacl->size, and the current code accepts it during SMB2_CREATE access validation, while parse_dacl() and smb_inherit_dacl() stop at pdacl_size. Bound both ACE walks by pdacl_size to match the DACL boundary semantics used elsewhere in the server. Validation: - semantic KUnit harness shows the post-boundary ACE is selected before the fix and rejected (EACCES) after it - linux master (7.2-rc6), x86_64

HighCVSS 8.1 · v3.1—No exploit Fix available
Published
Sep 17, 2026
Updated
Oct 30, 2026
EPSS
0.4% · 41th percentile
CWE
—

Report tools

JSON

Action score

32

Monitor

Low priority for now.

CVSS
32 / 40 · 8.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CNA vs NVD score

NVD
—
CNA · Linux
8.1
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.

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  • 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-2026-90153

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.

—

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

    • cb69d4d6f709f87c94afa28ae64c501576692171, 6e8f4abf584253cbaa596ea4ad13110cf61cd4c9, 8e33102309bd6839b2e2e158f93a7b378cb4655d, 6.0affected
    • 8f0541186e9ad1b62accc9519cc2b7a7240272a7 and later · before 930dcdd888eabf166589e020dcbf6d15b5e13305affected · git
    • 8f0541186e9ad1b62accc9519cc2b7a7240272a7 and later · before a2051ffe452afad52f580b85a3fd8851933b1e7caffected · git
    • 8f0541186e9ad1b62accc9519cc2b7a7240272a7 and later · before a29f57a14c939586d84d7fd6a029bd1fd170098faffected · git
    • 8f0541186e9ad1b62accc9519cc2b7a7240272a7 and later · before a4a307d149327dad5fb25187e1b03cebd1b04de6affected · git
    • 8f0541186e9ad1b62accc9519cc2b7a7240272a7 and later · before 8e4f75e979c1d9a51b0a48ac33d0cfd5f039ec67affected · git
    • 8f0541186e9ad1b62accc9519cc2b7a7240272a7 and later · before 79decd88dd3f0d42e7fb0689b1a7853bfa302459affected · git
    • 5.15.62 and later · before 5.16affected · semver
    • 5.18.18 and later · before 5.19affected · semver
    • 5.19.2 and later · before 5.20affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.6-17.2.6-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-90151Sep 17, 2026 · NFSv4: remove callback IDR entry on client allocation failure
    39Monitor
  • ← EarlierCVE-2026-90152Sep 17, 2026 · smb/server: fix session leak in ksmbd_session_register()
    0Monitor
  • Later →CVE-2026-90154Sep 17, 2026 · ksmbd: scope session state changes to bound connections
    0Monitor

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 Linux5.16Vendor (CNA)
Linux Linux5.19Vendor (CNA)
Linux Linux5.20Vendor (CNA)
Linux Linux79decd88dd3f0d42e7fb0689b1a7853bfa302459Vendor (CNA)
Linux Linux8e4f75e979c1d9a51b0a48ac33d0cfd5f039ec67Vendor (CNA)
Linux Linux930dcdd888eabf166589e020dcbf6d15b5e13305Vendor (CNA)
Linux Linuxa2051ffe452afad52f580b85a3fd8851933b1e7cVendor (CNA)
Linux Linuxa29f57a14c939586d84d7fd6a029bd1fd170098fVendor (CNA)
Linux Linuxa4a307d149327dad5fb25187e1b03cebd1b04de6Vendor (CNA)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.111-1~deb12u1 · 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.

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.

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

Weakness class (CWE)

—

CVSS vector

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

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. Fix✗ → ✓

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References

Show all references (5 more)

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

All records