CVE-2026-53394
Received Received - Intake

Memory Leak in Linux Kernel NFS Daemon

Publication date: 2026-07-19

Last updated on: 2026-07-19

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: nfsd: avoid leaking pre-allocated openowner on unconfirmed retry race When find_or_alloc_open_stateowner() encounters an unconfirmed owner, it calls release_openowner() and sets oo = NULL. Control then falls through past the `if (oo)` guard -- which would have freed any pre-allocated `new` -- and unconditionally executes `new = alloc_stateowner(...)`. If `new` was already allocated on a prior iteration, the pointer is silently overwritten and the previous allocation (slab object + owner name buffer) is leaked. This requires a race: two NFSv4.0 OPEN threads with the same owner string, where a concurrent thread inserts a new unconfirmed owner into the hash between retry iterations. The window is narrow but repeatable under adversarial conditions. Fix by adding `goto retry` after `oo = NULL` so the already-allocated `new` is reused on the next iteration rather than overwritten.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-07-19
Last Modified
2026-07-19
Generated
2026-07-20
AI Q&A
2026-07-19
EPSS Evaluated
N/A
NVD
CVE-2026-53394
EUVD
EUVD-2026-45516

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-UNKNOWN

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

This is a memory leak vulnerability in the Linux kernel's NFS server (nfsd). It occurs when handling NFSv4.0 OPEN requests with the same owner string. A race condition causes the kernel to overwrite a pre-allocated memory structure without freeing it first, leading to a resource leak.

Detection Guidance

This vulnerability is specific to the Linux kernel's NFSv4.0 implementation and requires detecting race conditions in openowner handling. Monitor kernel logs for NFS-related errors or crashes, particularly during high-concurrency scenarios. Check for slab memory leaks in kernel memory allocators using tools like slabtop or vmstat. No direct detection commands are provided in the context.

Impact Analysis

The impact is primarily on system stability and resource usage. The leaked memory accumulates over time, potentially causing performance degradation or crashes due to exhaustion of kernel memory resources. Systems running NFSv4.0 servers are most affected.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards. It is a memory leak in the Linux kernel's NFSv4.0 implementation, which could lead to resource exhaustion but does not involve data breaches or unauthorized access.

Mitigation Strategies

Apply the latest Linux kernel patches that include the fix for CVE-2026-53394. If patching is not immediately possible, consider disabling NFSv4.0 until the update is applied. Monitor NFS server logs for unusual activity or crashes that may indicate exploitation attempts.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-53394. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart