CVE-2026-89690 Affecting kernel-debug package, versions <0:6.12.0-211.64.1.el10_2


Severity

Recommended
high

Based on Oracle Linux security rating.

Threat Intelligence

EPSS
0.16% (5th percentile)

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  • Snyk IDSNYK-ORACLE10-KERNELDEBUG-20885676
  • published13 Oct 2026
  • disclosed11 Sept 2026

Introduced: 11 Sep 2026

CVE-2026-89690  (opens in a new tab)

How to fix?

Upgrade Oracle:10 kernel-debug to version 0:6.12.0-211.64.1.el10_2 or higher.
This issue was patched in ELSA-2026-77690.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-debug package and not the kernel-debug package as distributed by Oracle. See How to fix? for Oracle:10 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

nfsd: defer vfree of compound ops to fix rpc_status UAF

The rpc_status netlink dumpit walks every in-flight svc_rqst under rcu_read_lock and, for NFSv4 requests, reads opnums out of args->ops[]. But args->ops is a separate vmalloc buffer freed synchronously by vfree() in nfsd4_release_compoundargs() at the end of every compound. The dumpit's rcu_read_lock pins the svc_rqst struct itself (freed via kfree_rcu), but nothing defers the vfree of the ops buffer across the RCU grace period. A concurrent compound completion can therefore free the buffer while the dumpit is reading it — a use-after-free on vmalloc memory.

The trailing seqcount recheck (smp_load_acquire of rq_status_counter) cannot undo a load that already retired against freed memory.

Fix by replacing vfree(args->ops) with kvfree_rcu_mightsleep(), which defers the free until after an RCU grace period. This makes the existing rcu_read_lock in the dumpit sufficient to protect the read. The tradeoff is that completed compound ops buffers (up to 200 * sizeof(struct nfsd4_op)) persist in memory slightly longer, across one grace period, before being reclaimed.

CVSS Base Scores

version 3.1