---
title: "CVE-2026-97557: Linux Kernel - Denial of Service"
description: "Linux kernel contains a reference count leak vulnerability in cifs_queue_oplock_break() caused by unconditional file reference increment before queueing work, letting attackers cause unmount failures, exploit requires interaction with slow-responding CIFS server."
url: https://panop.io/threat-heartbeat/CVE-2026-97557/
---

# CVE-2026-97557 Linux Kernel - Denial of Service

Linux kernel contains a reference count leak vulnerability in cifs\_queue\_oplock\_break() caused by unconditional file reference increment before queueing work, letting attackers cause unmount failures, exploit requires interaction with slow-responding CIFS server.

CVSS base score 7.5 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.66% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-97557)

## Details

Type

Denial of Service

Impact

Denial Of Service

CVSS vector

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

Published

25 September 2026

Updated

15 October 2026

## Vendor fix

Update to the latest Linux kernel version containing the fix for cifs\_queue\_oplock\_break() reference leak.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-97557](https://nvd.nist.gov/vuln/detail/CVE-2026-97557)
- [https://git.kernel.org/stable/c/2ed2c29dd9593637cfa25ac1eb23241b20202778](https://git.kernel.org/stable/c/2ed2c29dd9593637cfa25ac1eb23241b20202778)
- [https://git.kernel.org/stable/c/9f2e63f1b2d5fc5b5423424902c091123e220e7e](https://git.kernel.org/stable/c/9f2e63f1b2d5fc5b5423424902c091123e220e7e)
- [https://git.kernel.org/stable/c/af0193bbf1ac8c0f67f972998b0cc629d6116cf6](https://git.kernel.org/stable/c/af0193bbf1ac8c0f67f972998b0cc629d6116cf6)
- [https://git.kernel.org/stable/c/dfe7b750c7e069873a8a57a11c816831a235618a](https://git.kernel.org/stable/c/dfe7b750c7e069873a8a57a11c816831a235618a)
- [https://git.kernel.org/stable/c/735a3a610136ae10f381d0909dff38e5b5c5f056](https://git.kernel.org/stable/c/735a3a610136ae10f381d0909dff38e5b5c5f056)
- [https://git.kernel.org/stable/c/de2a6bcff2659bea40c7485115b57f0ae189fc01](https://git.kernel.org/stable/c/de2a6bcff2659bea40c7485115b57f0ae189fc01)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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