CVE Catalog

CVE-2026-89677

CriticalCVSS 9.8
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.16%

6th percentile - higher than 6% of all known CVEs

Summary

In the Linux kernel, nfsd4_create_file() may call fh_compose() with the wrong dentry. dentry_create() can hypothetically return a different dentry than the one passed in, potentially leading to a use-after-free. The fix moves the fh_compose() call until the final dentry is certain.

Risk Assessment

This can lead to a use-after-free and potential code execution or kernel crash. The situation occurs in rare cases, such as when the exported filesystem is NFS.

Recommendation

Update the Linux kernel to a version containing the fix that moves the fh_compose() call after the final dentry is determined. Avoid exporting NFS filesystems over NFS if possible.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: nfsd: fix possible fh_compose of wrong dentry in nfsd4_create_file() dentry_create() can hypothetically provide a different dentry than the one passed in. This could happen, for example, if the exported filesystem is NFS, and the server returned to OPEN a filehandle which matched a directory that was already in the dcache. Clearly this would not be expected! If this were to happen the dentry (child) that was already stored in resfhp could be freed and later dereferenced. We shouldn't call fh_compose() until we are certain that we have the final dentry, so this patch moved the fh_compose() call to two places: one for the case where the target already exists, and one after dentry_create() where it was created.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS