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CVE-2026-90176· NVD / CVE Program· CNA Linux

ksmbd: Do not skip lock checks for single-byte ranges

In the Linux kernel, the following vulnerability has been resolved: ksmbd: Do not skip lock checks for single-byte ranges check_lock_range() uses inclusive ranges. Its callers pass the end offset as start + length - 1, so start == end represents a valid single-byte range rather than an empty range. The start == end shortcut therefore skips mandatory byte-range lock checks for one-byte reads, writes, copychunk operations and one-byte truncate ranges. A conflicting lock covering that byte is not checked and the operation is allowed to proceed. Remove the shortcut. The truncate size == inode->i_size case is already handled by only calling check_lock_range() when the new size differs from the current file size.

HighCVSS 8.1 · v3.1—No exploit Fix available
Published
Sep 17, 2026
Updated
Sep 18, 2026
EPSS
0.5% · 42th percentile
CWE
—
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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 · 0.5%

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.

Affected systems

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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

    • 6.19affected
    • 52fcbb92e0d3acfd1448b2a43b6595d540da5295 and later · before a89cc145832e81c32199d4ca2e1ea8bd51ed601daffected · git
    • da29cd197246c85c0473259f1cad897d9d28faea and later · before 993e0158331d37c04da18efe551b5e1e35fb3078affected · git
    • a6f4cfa3783804336491e0edcb250c25f9b59d33 and later · before f751d6e39d4c937c45f8fedc66699aa7d2d52288affected · git
    • 571204e4758a528fbd67330bd4b0dfbdafb33dd8 and later · before 84c2d8e807ac489f5c91769293fb15dfdae8bae8affected · git
    • 5d510ac31626ed157d2182149559430350cf2104 and later · before 07a9e289ff7edcc004f58952405f8a65c4e37512affected · git
    • 5d510ac31626ed157d2182149559430350cf2104 and later · before d40c24634fe077a0dc91fd11fccf44ce12b454d5affected · git
    • 6.1.160 and later · before 6.1.188affected · semver
    • 6.6.120 and later · before 6.6.157affected · semver
    • 6.12.64 and later · before 6.12.110affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxall versions—
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
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  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan
  • CVE-2026-74309vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
    40Plan
  • CVE-2026-74280crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
    40Plan
  • CVE-2026-74279crypto: cavium/cpt - fix DMA cleanup using wrong loop index
    40Plan

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 Linux07a9e289ff7edcc004f58952405f8a65c4e37512Vendor (CNA)
Linux Linux6.1.188Vendor (CNA)
Linux Linux6.12.110Vendor (CNA)
Linux Linux6.18.52Vendor (CNA)
Linux Linux6.6.157Vendor (CNA)
Linux Linux84c2d8e807ac489f5c91769293fb15dfdae8bae8Vendor (CNA)
Linux Linux993e0158331d37c04da18efe551b5e1e35fb3078Vendor (CNA)
Linux Linuxa89cc145832e81c32199d4ca2e1ea8bd51ed601dVendor (CNA)
Linux Linuxd40c24634fe077a0dc91fd11fccf44ce12b454d5Vendor (CNA)
Linux Linuxf751d6e39d4c937c45f8fedc66699aa7d2d52288Vendor (CNA)
debian:linux6.12.111-1 · 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.

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.

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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.

Noroxi analysis

No Noroxi analysis for this record yet

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Change log

  1. Fix✗ → ✓

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

References

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

All records