smb: client: reject userspace cifs.idmap descriptions (CVE-2026-97564) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-97564

smb: client: reject userspace cifs.idmap descriptions

Answer in brief

CVE-2026-97564 records a Unknown severity vulnerability in smb: client: reject userspace cifs.idmap descriptions. 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 25, 2026Updated Sep 25, 2026Source checked Sep 25, 2026First seen by HOL Sep 25, 2026Material review Sep 25, 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	>=4d79dba0e00749fa40de8ef13a9b85ce57a1603b <e5964064e3fbe6325893408faff08ca33de0e2c3 \|\| >=4d79dba0e00749fa40de8ef13a9b85ce57a1603b <96751028c0d4dec785709ea3eb0ab38a4f2ded96 \|\| >=4d79dba0e00749fa40de8ef13a9b85ce57a1603b <1d3b24b16a0b013792e8f1e3ed060f0b46f537d1 \|\| >=4d79dba0e00749fa40de8ef13a9b85ce57a1603b <d9d7eeb0cea5b55b82888f443622fd8d4ee064f3	e5964064e3fbe6325893408faff08ca33de0e2c3, 96751028c0d4dec785709ea3eb0ab38a4f2ded96, 1d3b24b16a0b013792e8f1e3ed060f0b46f537d1, d9d7eeb0cea5b55b82888f443622fd8d4ee064f3
Linux/Linuxgeneric	3.0	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to e5964064e3fbe6325893408faff08ca33de0e2c3 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 25, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: smb: client: reject userspace cifs.idmap descriptions cifs.idmap key descriptions carry authority-bearing fields (owner and group SIDs and uid/gid values in "os:"/"gs:"/"oi:"/"gi:" form) that the cifs.idmap upcall helper treats as kernel-originating inputs. Unlike its sibling cifs.spnego, the cifs.idmap key type has no vet_description hook, so userspace can create keys of this type through request_key(2)/add_key(2) and supply those fields without CIFS origin. A request_key(2) call with a non-NULL callout then drives a root usermodehelper upcall (/sbin/request-key -> cifs.idmap) that consumes the unvetted description in root context. Only accept cifs.idmap descriptions while CIFS is using its private root_cred to request the key. id_to_sid()/sid_to_id() already run under override_creds(root_cred), so the kernel-originated path is unaffected. This mirrors commit 3da1fdf4efbc ("smb: client: reject userspace cifs.spnego descriptions"), which applied the same restriction to cifs.spnego.

Quoted source text, attributed separately from HOL analysis.