Bug 2532154 (CVE-2026-89701)

Summary:	CVE-2026-89701 kernel: nfsd: validate nseconds in TIME_DELEG decode paths
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's Network File System Daemon (nfsd). The TIME_DELEG_ACCESS and TIME_DELEG_MODIFY decode paths do not properly validate the nanosecond (nseconds) value in timestamps. This allows a remote attacker to provide a malformed timestamp, which can then be written to disk, potentially leading to data integrity issues or unexpected system behavior.	Story Points:	---
Clone Of:		Environment:
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Regression:	---	Mount Type:	---
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Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-11 20:59:33 UTC

In the Linux kernel, the following vulnerability has been resolved:

nfsd: validate nseconds in TIME_DELEG decode paths

The xdrgen-based TIME_DELEG_ACCESS and TIME_DELEG_MODIFY decode arms
store a raw uint32_t nseconds directly into tv_nsec without enforcing
nseconds < NSEC_PER_SEC. The legacy nfsd4_decode_nfstime4 has this
check but the TIME_DELEG paths do not. A malformed timespec can
propagate through notify_change() to disk.

Add range checks in both nfs4xdr.c (SETATTR path) and
nfs4callback.c (CB_GETATTR path).

Comment 1 Keith Grant 2026-09-21 13:29:51 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89701.mbox