---
cve: "CVE-2026-53198"
severity: "HIGH"
cvss: 8.8
epss: "44%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-06-25 09:16:37"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-07T07:49:22+02:00"
---

# CVE-2026-53198

> 8.8 HIGH

## Beschreibung

In the Linux kernel, the following vulnerability has been resolved:

ksmbd: fix use-after-free of a deferred file_lock on double SMB2_CANCEL

A deferred byte-range lock (an SMB2_LOCK that blocks) registers an async work on
conn->async_requests via setup_async_work(), with cancel_fn =
smb2_remove_blocked_lock and cancel_argv[0] pointing at the struct file_lock.

When the request is cancelled, the worker frees the file_lock with
locks_free_lock() and takes the cancelled early-exit, which "goto out"s and never
reaches release_async_work() -- the only site that unlinks the work from
conn->async_requests and clears cancel_fn/cancel_argv. The work therefore stays
matchable on async_requests with a live cancel_fn pointing at the freed file_lock,
until connection teardown finally runs release_async_work().

smb2_cancel() fires cancel_fn unconditionally with no state guard, so a second
SMB2_CANCEL for the same AsyncId, arriving in that window, re-runs
smb2_remove_blocked_lock() on the freed file_lock -- a slab use-after-free:

  BUG: KASAN: slab-use-after-free in __locks_delete_block
    __locks_delete_block
    locks_delete_block
    ksmbd_vfs_posix_lock_unblock
    smb2_remove_blocked_lock
    smb2_cancel

## CVSS-Vektor

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

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Gering | warn |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- Kernel ≥ 6.1.176
- Kernel ≥ 6.6.143
- Kernel ≥ 6.12.94
- Kernel ≥ 6.18.36
- Kernel ≥ 7.0.13

## Referenzen

- <https://git.kernel.org/stable/c/b7063c7426ea5a4d15e01b60538718765392f49d>
- <https://git.kernel.org/stable/c/0da2e073f9cbf4985a0fd9acb71bc5ff599f8afd>
- <https://git.kernel.org/stable/c/89ae9df09d2c1fb4a4eb495c113a7ce1dca34147>
- <https://git.kernel.org/stable/c/14d2eee0193ac3cd1bf3d014373449f0b8d35d6d>
- <https://git.kernel.org/stable/c/2b2eda2821cff1d1b5a423b6ee7d8fc6fbc8e694>
- <https://git.kernel.org/stable/c/f580d27e8928828693df44ba2db0fffdbe11dfea>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-53198) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_