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CVE-2026-89706

Vulnérabilité élevée dans Linux (Linux)

CVSS 7.5 · Élevée
EPSS 0.5%
Linux•Linux•Versions : <=6.1.*, <c6d2f6372c7e0f76b9c148ff7696aec64da0b5b7, <=6.12.*, eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d, 5.15.221, 5.10.270, 0, 7.2.4, <f5cb2276954cb80987a93ef9f9dfbfdbfc0f10b9, 6.1.188, <bf0cd31a9abcb728c17d79b4c2cc533612a8b6af, <5.14, <cc5f7cef0659a27c13dd33edd8e2f79257b095c6, <31d4d0a62ec4bafbcdbad142f11ab1f90794b1d0, <=5.10.*, <6b13d26cc21b6320a3c61d5e4cee2ce9a589b181, <=6.6.*, 5.14, 6.6.157, 817c6eb975798647c4bbbfc9eb288aa413ec7f65, <=6.18.*, <5.10.270, <=7.2.*, <591134e059e3456180244a826d6917cdc183140b, <=*, <=5.15.*, 6.18.50, 6.12.109, 5.10.220, <8a08ffe73eb2aa6bc6f88763da7e2b55bab6493a, 7.3

Description

In 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.

Gravité et risque d'exploitation

CVE-2026-89706 obtient un score CVSS de 7.5/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.53 %, ce qui la place devant 43.3 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <=6.1.*, <c6d2f6372c7e0f76b9c148ff7696aec64da0b5b7, <=6.12.*, eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d, 5.15.221, 5.10.270, 0, 7.2.4, <f5cb2276954cb80987a93ef9f9dfbfdbfc0f10b9, 6.1.188, <bf0cd31a9abcb728c17d79b4c2cc533612a8b6af, <5.14, <cc5f7cef0659a27c13dd33edd8e2f79257b095c6, <31d4d0a62ec4bafbcdbad142f11ab1f90794b1d0, <=5.10.*, <6b13d26cc21b6320a3c61d5e4cee2ce9a589b181, <=6.6.*, 5.14, 6.6.157, 817c6eb975798647c4bbbfc9eb288aa413ec7f65, <=6.18.*, <5.10.270, <=7.2.*, <591134e059e3456180244a826d6917cdc183140b, <=*, <=5.15.*, 6.18.50, 6.12.109, 5.10.220, <8a08ffe73eb2aa6bc6f88763da7e2b55bab6493a, 7.3) est présent sur votre parc.
  • Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
  • À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
  • Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

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