cifs: clear tcon after cifsFileInfo_put() in cifs_file_set_size() (CVE-2026-89641) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-89641

cifs: clear tcon after cifsFileInfo_put() in cifs_file_set_size()

Answer in brief

CVE-2026-89641 records a Unknown severity vulnerability in cifs: clear tcon after cifsFileInfo_put() in cifs_file_set_size(). 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 11, 2026Updated Sep 11, 2026Source checked Sep 11, 2026First seen by HOL Sep 11, 2026Material review Sep 11, 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	>=110fee6b9bb58a5c50047fc2594d415f741b591e <4f18c9e7ee464aaae5cd9fccdb943b3fcb4655d4 \|\| >=110fee6b9bb58a5c50047fc2594d415f741b591e <4bea15d9c7683218f57b8c1f5f0aa75cab76af8d \|\| >=110fee6b9bb58a5c50047fc2594d415f741b591e <b96db32fed8dfb2478d7c208f89bf383beed1535	4f18c9e7ee464aaae5cd9fccdb943b3fcb4655d4, 4bea15d9c7683218f57b8c1f5f0aa75cab76af8d, b96db32fed8dfb2478d7c208f89bf383beed1535
Linux/Linuxgeneric	6.18	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 4f18c9e7ee464aaae5cd9fccdb943b3fcb4655d4 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 11, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: cifs: clear tcon after cifsFileInfo_put() in cifs_file_set_size() When the else branch of cifs_file_set_size() finds a writable file handle via find_writable_file(), it borrows tcon and server from the handle's tlink, attempts the handle-based set_file_size() RPC, and then releases the handle with cifsFileInfo_put(). If set_file_size() fails, execution falls through to the path-based fallback, which reuses the borrowed tcon and server under the "if (tcon == NULL)" guard. Since tcon is not NULL at that point, the guard is skipped. If cifsFileInfo_put() dropped the last reference on a tlink that was already removed from the tlink tree (TCON_LINK_IN_TREE cleared, as happens during reconnection or session teardown), cifs_put_tlink() will have freed tcon; the subsequent set_path_size() call is then a use-after-free. Setting tcon = NULL after cifsFileInfo_put() causes the existing guard to take the cifs_sb_tlink() path, which acquires a fresh reference for the path-based operation or fails cleanly if the session is gone.

Quoted source text, attributed separately from HOL analysis.