Lock held while waiting for lease break in Linux ksmbd
Key facts
- Attack vector
- —
- Privileges required
- —
- User interaction
- —
- Attack complexity
- —
- Impact type
- —
- Confidentiality · integrity · availability
- —
- Fix status
- Partial Red Hat: 1 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
The ksmbd SMB server in the Linux kernel holds a lock while it waits for a client to acknowledge a lease break. When a client caches a read-handle lease through deferred close and a conflicting open arrives, the client's close path blocks on that lock, so the break is resolved only by a 35 second timeout. Linux kernel versions from 6.6.35 before 6.7 and from 6.9 are affected.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
In the Linux kernel, the following vulnerability has been resolved: ksmbd: don't hold ci->m_lock while waiting for a lease break ack When a cifs.ko client caches a read-handle (RH) lease via deferred close and a conflicting open arrives, ksmbd breaks the lease and waits for the acknowledgment in wait_for_break_ack() for up to OPLOCK_WAIT_TIME (35s). __smb_break_all_levII_oplock() runs that wait while holding ci->m_lock for read. cifs.ko reacts to a handle-lease break by closing the deferred handle rather than sending a lease break acknowledgment. That close path (close_id_del_oplock() -> opinfo_del()) takes ci->m_lock for write and is exactly what would wake the waiter, but it blocks on the read lock held by the waiting thread. The break is then resolved only by the 35s timeout, so xfstests generic/001 takes ~78s with leases enabled versus ~4s with oplocks only. Collect the target opinfos (each pinned with a reference) while holding ci->m_lock, then break them after releasing it, matching how smb_grant_oplock() already breaks a conflicting lease using only a reference. The reference keeps the opinfo (and its conn and lease) alive across the unlocked window, and a close racing the break is handled by the existing OPLOCK_CLOSING state check. Apply the same fix to the parent lease break paths.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
The fix is in Linux kernel 6.7, 6.18.53 and 7.2. The sources list no fixed version for Red Hat Enterprise Linux 10.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA Linux (Linux) Fixed in 6.7
- Fix · CNA Linux (Linux) Fixed in 6.18.53, 7.2
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
Not affected: 6 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4
- Red Hat OpenShift Container Platform 5
Timeline
- 2026-10-23 Threatist record created from CVE-2026-98897
- 2026-10-23 Alias added: GHSA-83j5-g9m2-9mf4
- 2026-10-26 Fix available: Linux/Linux@0, Linux/[email protected] · CNA
- 2026-10-26 Affected versions changed · Red Hat
- 2026-10-26 CVSS score added · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
References
More Linux vulnerabilities
- TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
- TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
- TI-2021-02452 Incorrect authorization in Ubuntu linux kernel KEVCVSS 3.1HIGH 8.8
- TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
- TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
- TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
Sources
- CVE-2026-98897 · CVE Program
- CVE-2026-98897 · NVD
- FIRST EPSS
- GHSA-83j5-g9m2-9mf4 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98897 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences