Is CVE-2026-89712 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-89712 being exploited in the wild.

How severe is CVE-2026-89712?

Critical severity, with a CVSS score of 9.8, published 11 September 2026.

Which products and versions are affected?

Linux Kernel Multiple versions (2.6.11 through 6.x series affected; patched in stable branches).

Is there a fix for CVE-2026-89712?

A patch was published on 2026-08-03: Patch merged in kernel mainline (commit 036c1b182f4da65363e79ec0ac276edc6b7296e5) Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-89712 attacked?

It is attacked over the network, in an operating system.

Am I affected by CVE-2026-89712?

Check whether you run Linux Kernel at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-89712: Linux kernel NFSD use-after-free in ssc_expire_umount

CVE-2026-89712 · Severity: critical · CVSS 9.8 · Published 2026-09-11

The Linux kernel's NFS server (NFSD) contains a use-after-free vulnerability in the inter-server copy mount management code. When processing expired mount entries, the code temporarily releases a lock and continues iterating using a saved pointer that can be freed by concurrent operations, leading to memory corruption. An attacker with network access to an NFS server could trigger a kernel crash or potentially execute code.

Technologies: Linux Kernel. Vendors: Linux.

Quick answers

Is CVE-2026-89712 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-89712 being exploited in the wild.
How severe is CVE-2026-89712?: Critical severity, with a CVSS score of 9.8, published 11 September 2026.
Which products and versions are affected?: Linux Kernel Multiple versions (2.6.11 through 6.x series affected; patched in stable branches).
Is there a fix for CVE-2026-89712?: A patch was published on 2026-08-03: Patch merged in kernel mainline (commit 036c1b182f4da65363e79ec0ac276edc6b7296e5) Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-89712 attacked?: It is attacked over the network, in an operating system.
Am I affected by CVE-2026-89712?: Check whether you run Linux Kernel at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability is a use-after-free in the nfsd4_ssc_expire_umount() function within the Linux kernel's NFS server implementation (fs/nfsd/nfs4state.c). The function walks a list of mount entries using list_for_each_entry_safe() to iterate while releasing the nfsd_ssc_lock during mntput() operations. While the current entry is protected by the nsui_busy flag, the saved next pointer (tmp) is not pinned and can be freed by concurrent nfsd4_ssc_cancel_dul() calls from other RPC threads during the lock-drop window, causing dereferencing of freed memory on the next iteration. The fix restarts the walk from the list head after each unlock window rather than relying on a saved next pointer. The vulnerability affects inter-server copy operations in NFS, which are network-accessible and require no authentication beyond normal NFS access controls. A patch is available in the Linux kernel stable trees.

Affected products

Linux Linux kernel Multiple versions (2.6.11 through 6.x series affected; patched in stable branches)

Timeline

2026-09-11: disclosed: CVE-2026-89712 disclosed
2026-08-03: patched: Patch merged in kernel mainline (commit 036c1b182f4da65363e79ec0ac276edc6b7296e5)
2026-09-14: patched: Patch released in stable kernels via Greg Kroah-Hartman

References

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