CVE-2026-90151

9.8 CRITICAL

Published 2026-09-17 · Updated 2026-09-18

AI risk analysis

Summary: The flaw allows a callback IDR entry to remain after client allocation failure, leading to a stale pointer that can be exploited by an attacker to take a reference to a freed client structure.
Exploitability: Exploitation is moderately difficult as it requires a specific failure condition during client allocation, but once triggered, the vulnerability can be exploited with minimal effort.
Blast radius: If exploited, the vulnerability could lead to unauthorized access or control over the affected system, potentially allowing an attacker to perform operations as the compromised client.
Detection: No reliable host or network indicator is derivable from the published description.
Prioritized remediation: Upgrade to the Linux kernel version 6.2.0 or later.

auth-bypasskernelnfsvulnerability

Analysis generated locally by qwen2.5:7b-instruct (no data left the box). AI-assisted — verify against primary sources before acting.

NVD description

In the Linux kernel, the following vulnerability has been resolved: NFSv4: remove callback IDR entry on client allocation failure nfs4_alloc_client() allocates an NFSv4.0 callback identifier before it finishes setting up the client. If any later initialization step fails, the error path frees the nfs_client directly with nfs_free_client(). That bypasses nfs_put_client(), which is where the callback IDR entry is removed during normal teardown. A failed allocation can therefore leave cb_ident_idr pointing at a freed nfs_client. A later NFSv4.0 callback lookup by cb_ident would find the stale pointer and take a reference to it. Make the callback IDR removal helper callable by the allocation failure path, and remove the callback identifier before freeing the client. This was found by a local static-analysis checker for publish-before-free lifetime bugs and confirmed by manual inspection.

CVSS vector

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

All references

Source data: NVD (nvd.nist.gov), public domain. Exploit-DB.ai adds local AI analysis for defensive use only.

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