CVE-2026-90038

CRITICAL
Published Sep 16, 2026 Modified Sep 16, 2026

Description

In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent client use-after-free during export state revocation nfsd4_revoke_export_states() has the same use-after-free as nfsd4_revoke_states(): it drops nn->client_lock across revoke_one_stid() and the following read of clp->cl_minorversion, but the stateid reference it holds does not pin the client. A teardown racing the dropped lock can free the client while revoke_one_stid() still dereferences it. exportfs -u drives this path through NFSD_CMD_UNLOCK_EXPORT, so an administrator removing an export can race a client expiry. Skip a client that is already expiring and otherwise pin it with cl_rpc_users under client_lock before dropping the lock, matching nfsd4_revoke_states().

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CVSS v3.1 Score

9.8
CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References

Frequently Asked Questions

What is CVE-2026-90038? +
In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent client use-after-free during export state revocation nfsd4_revoke_export_states() has the same use-after-free as nfsd4_revoke_states(): it drops nn->client_lock across revoke_one_stid() and the following read of clp->cl_minorversion, but the stateid reference it holds does not pin the client. A teardown racing the dropped lock can free the client while revoke_one_stid() still dereferences it. exportfs -u drives this path through NFSD_CMD_UNLOCK_EXPORT, so an administrator removing an export can race a client expiry. Skip a client that is already expiring and otherwise pin it with cl_rpc_users under client_lock before dropping the lock, matching nfsd4_revoke_states(). It has a CVSS v3.1 base score of 9.8 (CRITICAL).
How severe is CVE-2026-90038? +
CVE-2026-90038 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately.
How do I check if I'm vulnerable to CVE-2026-90038? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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