CVE-2025-40326
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-12-08

Last updated on: 2025-12-08

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: NFSD: Define actions for the new time_deleg FATTR4 attributes NFSv4 clients won't send legitimate GETATTR requests for these new attributes because they are intended to be used only with CB_GETATTR and SETATTR. But NFSD has to do something besides crashing if it ever sees a GETATTR request that queries these attributes. RFC 8881 Section 18.7.3 states: > The server MUST return a value for each attribute that the client > requests if the attribute is supported by the server for the > target file system. If the server does not support a particular > attribute on the target file system, then it MUST NOT return the > attribute value and MUST NOT set the attribute bit in the result > bitmap. The server MUST return an error if it supports an > attribute on the target but cannot obtain its value. In that case, > no attribute values will be returned. Further, RFC 9754 Section 5 states: > These new attributes are invalid to be used with GETATTR, VERIFY, > and NVERIFY, and they can only be used with CB_GETATTR and SETATTR > by a client holding an appropriate delegation. Thus there does not appear to be a specific server response mandated by specification. Taking the guidance that querying these attributes via GETATTR is "invalid", NFSD will return nfserr_inval, failing the request entirely.
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Meta Information
Published
2025-12-08
Last Modified
2025-12-08
Generated
2026-05-07
AI Q&A
2025-12-08
EPSS Evaluated
2026-05-05
NVD
CVE-2025-40326
EUVD
EUVD-2025-201620
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
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AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability involves the Linux kernel's NFS server daemon (NFSD) handling of new time_deleg FATTR4 attributes in NFSv4. NFSv4 clients do not send legitimate GETATTR requests for these new attributes because they are only meant for use with CB_GETATTR and SETATTR operations. However, if the server receives a GETATTR request querying these attributes, it previously could crash. The fix ensures that instead of crashing, the server returns an error (nfserr_inval) when such invalid GETATTR requests are received, complying with RFC specifications.


How can this vulnerability impact me? :

If unpatched, this vulnerability could cause the NFS server to crash when it receives invalid GETATTR requests for the new time_deleg attributes, potentially leading to denial of service or instability in systems relying on NFSv4. The fix prevents crashes by returning an error instead, improving server stability and reliability.


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