CVE-2026-89685

nfsd: fix clock domain mismatch in clients_still_reclaiming()

HIGH
7.5
CVSS Score
Published: September 11, 2026 at 07:46 PM UTC
Updated: October 21, 2026 at 01:20 PM UTC
1 product affected across 1 vendorLinux Kernel

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Severity
HIGH7.5
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: fix clock domain mismatch in clients_still_reclaiming() clients_still_reclaiming() computes a deadline from nn->boot_time (CLOCK_REALTIME, ~1.7 billion) but compares it against ktime_get_boottime_seconds() (CLOCK_BOOTTIME, seconds since boot). The comparison is always false — it would take ~54 years of uptime for BOOTTIME to exceed the REALTIME-derived deadline. This means any client can hold the server in grace indefinitely by sending CLAIM_PREVIOUS OPEN requests, blocking all non-reclaim operations for all other clients. Add boot_time_bt (CLOCK_BOOTTIME) alongside the existing boot_time and use it for the deadline computation. boot_time (CLOCK_REALTIME) is preserved for its cl_boot clientid-nonce role.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

20b7d86f29d39e8ae19bb29c24ffee70dc385ddf5.6
Vendor states this is fixed in 09ea3eb9a518565f5bca386e81b993ed8825f5e8 (fixed)
Vendor states this is fixed in 9843649196221152b6e5d138a3ce859bdaae1d96 (fixed)
Vendor states this is fixed in e92e80c5b043108029bc729b30d12c37158fb9cb (fixed)
Vendor states this is fixed in f9cec313efb2fd18d962aad738a4892bce806016 (fixed)
Vendor states this is fixed in 5.6 (unaffected)
Vendor states this is fixed in 6.12.111 (unaffected)
Vendor states this is fixed in 6.18.51 (unaffected)
Vendor states this is fixed in 6.6.160 (unaffected)
Vendor states this is fixed in 7.2.4 (unaffected)
Vendor states this is fixed in 7.3 (unaffected)
Vendor states this is fixed in 7.3-rc1 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHLinux
Vector?

Quick Info

StatusRECEIVED

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