CVE-2026-97557smb: client: avoid leaking refcount in cifs_queue_oplock_break()
- 7.5HighCVSS base score
- 0.70%Exploitation in 30 daysEPSS · top 46% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
In the Linux kernel, the following vulnerability has been resolved: smb: client: avoid leaking refcount in cifs_queue_oplock_break() cifs_queue_oplock_break() unconditionally takes a reference on the target file before queueing cifs_oplock_break(). Only that work item decreases the reference counter again. If another oplock break arrives while that work is still queued, queue_work() will return false and not queue this second work item. As a result, we will never reach the point to drop the file reference again and are leaking this reference. This can be triggered when interacting with a slow-responding server. As a result, later unmount operations for this file system will fail with BUG: Dentry ... still in use (1) [unmount of cifs cifs] VFS: Busy inodes after unmount of cifs (cifs) kernel BUG at fs/super.c:777! Fix this by only incrementing the reference count if the work has been queued successfully. Taking it after queue_work() is safe because all three callers hold tcon->open_file_lock across the call and _cifsFileInfo_put() decrements under that same lock, so a worker that starts the handler in the window cannot drop the reference before it has been taken.
Timeline
ID reserved
By Linux
- 1 day later
· 1 day later
Published
- 35 days later
· 35 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Received | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.70% · top 46% of all CVEs (15 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Affected products
- affected b98749cac4a695f084a5ff076f4510b23e353ecd – < 13b9519b19e6e58a6cd01e63062cd1da7bd6449a
- affected b98749cac4a695f084a5ff076f4510b23e353ecd – < 0fb92ac85db58945ad7b970ff17674001487b3a3
- affected b98749cac4a695f084a5ff076f4510b23e353ecd – < 735a3a610136ae10f381d0909dff38e5b5c5f056
- affected b98749cac4a695f084a5ff076f4510b23e353ecd – < de2a6bcff2659bea40c7485115b57f0ae189fc01
- affected b98749cac4a695f084a5ff076f4510b23e353ecd – < af0193bbf1ac8c0f67f972998b0cc629d6116cf6
- affected b98749cac4a695f084a5ff076f4510b23e353ecd – < 2ed2c29dd9593637cfa25ac1eb23241b20202778
- affected b98749cac4a695f084a5ff076f4510b23e353ecd – < dfe7b750c7e069873a8a57a11c816831a235618a
- affected b98749cac4a695f084a5ff076f4510b23e353ecd – < 9f2e63f1b2d5fc5b5423424902c091123e220e7e
- affected 2429fcf06d3cb962693868ab0a927c9038f12a2d
- affected 1ee4f2d7cdcd4508cc3cbe3b2622d7177b89da12
- affected 53fc31a4853e30d6e8f142b824f724da27ff3e40
- affected 8092ecc306d81186a64cda42411121f4d35aaff4
- affected ebac4d0adf68f8962bd82fcf483936edd6ec095b
- affected 3.16.72 – < 3.17
- affected 4.9.171 – < 4.10
- affected 4.14.114 – < 4.15
- affected 4.19.37 – < 4.20
- affected 5.0.10 – < 5.1
- affected 5.1
- unaffected < 5.1
- unaffected 5.10.273 – ≤ 5.10.*
- unaffected 5.15.224 – ≤ 5.15.*
- unaffected 6.1.189 – ≤ 6.1.*
- unaffected 6.6.158 – ≤ 6.6.*
- unaffected 6.12.111 – ≤ 6.12.*
- unaffected 6.18.53 – ≤ 6.18.*
- unaffected 7.2.7 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
References8
- https://git.kernel.org/stable/c/13b9519b19e6e58a6cd01e63062cd1da7bd6449a (opens in a new tab)
- https://git.kernel.org/stable/c/0fb92ac85db58945ad7b970ff17674001487b3a3 (opens in a new tab)
- https://git.kernel.org/stable/c/735a3a610136ae10f381d0909dff38e5b5c5f056 (opens in a new tab)
- https://git.kernel.org/stable/c/de2a6bcff2659bea40c7485115b57f0ae189fc01 (opens in a new tab)
- https://git.kernel.org/stable/c/af0193bbf1ac8c0f67f972998b0cc629d6116cf6 (opens in a new tab)
- https://git.kernel.org/stable/c/2ed2c29dd9593637cfa25ac1eb23241b20202778 (opens in a new tab)
- https://git.kernel.org/stable/c/dfe7b750c7e069873a8a57a11c816831a235618a (opens in a new tab)
- https://git.kernel.org/stable/c/9f2e63f1b2d5fc5b5423424902c091123e220e7e (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-86865 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-97557)Record last updated .