nfsd: Reset write verifier when async COPY writeback fails

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89706
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:57 UTC
Updated2026-09-14 13:19:20 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: nfsd: Reset write verifier when async COPY writeback fails Async COPY captures nn->writeverf at request time and reports it to the client via CB_OFFLOAD after the worker kthread completes. When the post-copy vfs_fsync_range() or filemap_check_wb_err() in _nfsd_copy_file_range() reports an error, the worker correctly leaves NFSD4_COPY_F_COMMITTED clear so that CB_OFFLOAD encodes wr_stable_how as NFS_UNSTABLE, but the server's write verifier is not rotated. A client that receives NFS_UNSTABLE in CB_OFFLOAD follows up with COMMIT to make the copied data durable. With the verifier unchanged, COMMIT returns the same value the client just received via CB_OFFLOAD, and the client concludes the copy is durable -- silently dropping the data whose writeback in fact failed. This violates the UNSTABLE+COMMIT durability contract (RFC 7862 section 15.1, RFC 8881 section 18.32) and matches the bug just fixed in nfsd_vfs_write() and nfsd_commit(). Rotate nn->writeverf at the writeback-failure site. The async COPY worker has no svc_rqst, so commit_reset_write_verifier() is not available here; calling nfsd_reset_write_verifier() directly mirrors the trace-less reset already used by nfsd_file_check_write_error() for the same purpose. Filter out -EAGAIN and -ESTALE, matching commit_reset_write_verifier(), since neither indicates a durable-storage failure.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

EPSS: 0.004440000 probability, percentile 0.374920000 (date 2026-09-14)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 817c6eb975798647c4bbbfc9eb288aa413ec7f65 cc5f7cef0659a27c13dd33edd8e2f79257b095c6 git Not specified
CNA Linux Linux affected eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d c6d2f6372c7e0f76b9c148ff7696aec64da0b5b7 git Not specified
CNA Linux Linux affected eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d 8a08ffe73eb2aa6bc6f88763da7e2b55bab6493a git Not specified
CNA Linux Linux affected eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d 6b13d26cc21b6320a3c61d5e4cee2ce9a589b181 git Not specified
CNA Linux Linux affected eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d 31d4d0a62ec4bafbcdbad142f11ab1f90794b1d0 git Not specified
CNA Linux Linux affected eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d 591134e059e3456180244a826d6917cdc183140b git Not specified
CNA Linux Linux affected eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d bf0cd31a9abcb728c17d79b4c2cc533612a8b6af git Not specified
CNA Linux Linux affected eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d f5cb2276954cb80987a93ef9f9dfbfdbfc0f10b9 git Not specified
CNA Linux Linux affected 5.10.220 5.10.270 semver Not specified
CNA Linux Linux affected 5.14 Not specified
CNA Linux Linux unaffected 5.14 semver Not specified
CNA Linux Linux unaffected 5.10.270 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.221 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.188 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.157 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.109 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.50 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/31d4d0a62ec4bafbcdbad142f11ab1f90794b1d0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6b13d26cc21b6320a3c61d5e4cee2ce9a589b181 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f5cb2276954cb80987a93ef9f9dfbfdbfc0f10b9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/cc5f7cef0659a27c13dd33edd8e2f79257b095c6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c6d2f6372c7e0f76b9c148ff7696aec64da0b5b7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/bf0cd31a9abcb728c17d79b4c2cc533612a8b6af 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8a08ffe73eb2aa6bc6f88763da7e2b55bab6493a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/591134e059e3456180244a826d6917cdc183140b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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