Kernel crash via queued oplock reference leak
Published Sep 25, 2026 · Updated Sep 25, 2026
Resource leak in the Linux CIFS client allows context-dependent attackers to crash the kernel via oplock breaks from a slow SMB server. cifs_queue_oplock_break() increments a file reference before queue_work(), but a second request is not queued and therefore never releases that reference. Reachability requires an active CIFS mount with oplocks and overlapping breaks; the leaked reference makes a later unmount hit busy-inode checks and a kernel BUG.
Summary
What happened
Resource leak in the Linux CIFS client allows context-dependent attackers to crash the kernel via oplock breaks from a slow SMB server. cifs_queue_oplock_break() increments a file reference before queue_work(), but a second request is not queued and therefore never releases that reference. Reachability requires an active CIFS mount with oplocks and overlapping breaks; the leaked reference makes a later unmount hit busy-inode checks and a kernel BUG.
The record
- CVE
- CVE-2026-97557
- Published
- Sep 25, 2026
- Updated
- Sep 25, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1499.004
- Attack vector
- network
- Privileges
- Unavailable
Timeline
How it unfolded
- Sep 25, 2026CVE publishedPublication date reported by the CVE source.
- Sep 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=1ee4f2d7cdcd4508cc3cbe3b2622d7177b89da12
- Affected versionversion=2429fcf06d3cb962693868ab0a927c9038f12a2d
- Affected versionversion=3.16.72 <3.17
- Affected versionversion=4.14.114 <4.15
- Affected versionversion=4.19.37 <4.20
- Affected versionversion=4.9.171 <4.10
- Affected versionversion=5.0.10 <5.1
- Affected versionversion=5.1
- Affected versionversion=53fc31a4853e30d6e8f142b824f724da27ff3e40
- Affected versionversion=8092ecc306d81186a64cda42411121f4d35aaff4
- Affected versionversion=b98749cac4a695f084a5ff076f4510b23e353ecd <2ed2c29dd9593637cfa25ac1eb23241b20202778
- Affected versionversion=b98749cac4a695f084a5ff076f4510b23e353ecd <9f2e63f1b2d5fc5b5423424902c091123e220e7e
- Affected versionversion=b98749cac4a695f084a5ff076f4510b23e353ecd <af0193bbf1ac8c0f67f972998b0cc629d6116cf6
- Affected versionversion=b98749cac4a695f084a5ff076f4510b23e353ecd <dfe7b750c7e069873a8a57a11c816831a235618a
- Affected versionversion=ebac4d0adf68f8962bd82fcf483936edd6ec095b
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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