ksmbd: Do not skip lock checks for single-byte ranges (CVE-2026-90176) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-90176

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

Answer in brief

CVE-2026-90176 records a Unknown severity vulnerability in ksmbd: Do not skip lock checks for single-byte ranges. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 17, 2026Updated Sep 17, 2026Source checked Sep 17, 2026First seen by HOL Sep 17, 2026Material review Sep 17, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=52fcbb92e0d3acfd1448b2a43b6595d540da5295 <a89cc145832e81c32199d4ca2e1ea8bd51ed601d \|\| >=da29cd197246c85c0473259f1cad897d9d28faea <993e0158331d37c04da18efe551b5e1e35fb3078 \|\| >=a6f4cfa3783804336491e0edcb250c25f9b59d33 <f751d6e39d4c937c45f8fedc66699aa7d2d52288 \|\| >=571204e4758a528fbd67330bd4b0dfbdafb33dd8 <84c2d8e807ac489f5c91769293fb15dfdae8bae8 \|\| >=5d510ac31626ed157d2182149559430350cf2104 <07a9e289ff7edcc004f58952405f8a65c4e37512 \|\| >=5d510ac31626ed157d2182149559430350cf2104 <d40c24634fe077a0dc91fd11fccf44ce12b454d5 \|\| >=6.1.160 <6.1.188 \|\| >=6.6.120 <6.6.157 \|\| >=6.12.64 <6.12.110 \|\| >=6.18.3 <6.18.52	a89cc145832e81c32199d4ca2e1ea8bd51ed601d, 993e0158331d37c04da18efe551b5e1e35fb3078, f751d6e39d4c937c45f8fedc66699aa7d2d52288, 84c2d8e807ac489f5c91769293fb15dfdae8bae8, 07a9e289ff7edcc004f58952405f8a65c4e37512, d40c24634fe077a0dc91fd11fccf44ce12b454d5, 6.1.188, 6.6.157, 6.12.110, 6.18.52
Linux/Linuxgeneric	6.19	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to a89cc145832e81c32199d4ca2e1ea8bd51ed601d if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 17, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.