# CVE-2026-89685

## Summary

- **CVE ID:** CVE-2026-89685
- **Severity:** HIGH
- **CVSS Score:** 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
- **CWE:** N/A
- **Published:** Sep 11, 2026
- **Last Modified:** Sep 13, 2026

## 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 Products

- Linux — Linux (20b7d86f29d39e8ae19bb29c24ffee70dc385ddf)
- Linux — Linux (5.6)
- Linux — Linux (0)
- Linux — Linux (6.18.51)
- Linux — Linux (7.2.4)
- Linux — Linux (7.3-rc1)

## References

- [CNA](https://git.kernel.org/stable/c/f9cec313efb2fd18d962aad738a4892bce806016)
- [CNA](https://git.kernel.org/stable/c/9843649196221152b6e5d138a3ce859bdaae1d96)
- [CNA](https://git.kernel.org/stable/c/09ea3eb9a518565f5bca386e81b993ed8825f5e8)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.43%
- **EPSS Percentile:** 36.7

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._