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CVE-2026-31402

Vulnérabilité critique dans Linux (Linux)

CVSS 9.8 · Critique
EPSS 1.2%
Linux•Linux•Versions : <c9452c0797c95cf2378170df96cf4f4b3bca7eff, <=6.1.*, <dad0c3c0a8e5d1d6eb0fc455694ce3e25e6c57d0, <=6.12.*, 2.6.12, 6.12.78, 0, 7.0, <2.6.12, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 5.15.210, <=5.10.*, <=6.6.*, <ae8498337dfdfda71bdd0b807c9a23a126011d76, <0f0e2a54a31a7f9ad2915db99156114872317388, <=6.19.*, <2665887a69437a8a4f552f69509eecfb73d4aa19, <f9fcb4441f6c02bb20c2eb340101e27dfe23607c, <8afb437ea1f70cacb4bbdf11771fb5c4d720b965, <=6.18.*, 6.1.167, <=*, 5.10.253, <=5.15.*, 6.19.10, 6.6.130, 6.18.20, <5133b61aaf437e5f25b1b396b14242a6bb0508e2

Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: fix heap overflow in NFSv4.0 LOCK replay cache The NFSv4.0 replay cache uses a fixed 112-byte inline buffer (rp_ibuf[NFSD4_REPLAY_ISIZE]) to store encoded operation responses. This size was calculated based on OPEN responses and does not account for LOCK denied responses, which include the conflicting lock owner as a variable-length field up to 1024 bytes (NFS4_OPAQUE_LIMIT). When a LOCK operation is denied due to a conflict with an existing lock that has a large owner, nfsd4_encode_operation() copies the full encoded response into the undersized replay buffer via read_bytes_from_xdr_buf() with no bounds check. This results in a slab-out-of-bounds write of up to 944 bytes past the end of the buffer, corrupting adjacent heap memory. This can be triggered remotely by an unauthenticated attacker with two cooperating NFSv4.0 clients: one sets a lock with a large owner string, then the other requests a conflicting lock to provoke the denial. We could fix this by increasing NFSD4_REPLAY_ISIZE to allow for a full opaque, but that would increase the size of every stateowner, when most lockowners are not that large. Instead, fix this by checking the encoded response length against NFSD4_REPLAY_ISIZE before copying into the replay buffer. If the response is too large, set rp_buflen to 0 to skip caching the replay payload. The status is still cached, and the client already received the correct response on the original request.

Gravité et risque d'exploitation

CVE-2026-31402 obtient un score CVSS de 9.8/10, soit une gravité critique. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 1.20 %, ce qui la place devant 67.7 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <c9452c0797c95cf2378170df96cf4f4b3bca7eff, <=6.1.*, <dad0c3c0a8e5d1d6eb0fc455694ce3e25e6c57d0, <=6.12.*, 2.6.12, 6.12.78, 0, 7.0, <2.6.12, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 5.15.210, <=5.10.*, <=6.6.*, <ae8498337dfdfda71bdd0b807c9a23a126011d76, <0f0e2a54a31a7f9ad2915db99156114872317388, <=6.19.*, <2665887a69437a8a4f552f69509eecfb73d4aa19, <f9fcb4441f6c02bb20c2eb340101e27dfe23607c, <8afb437ea1f70cacb4bbdf11771fb5c4d720b965, <=6.18.*, 6.1.167, <=*, 5.10.253, <=5.15.*, 6.19.10, 6.6.130, 6.18.20, <5133b61aaf437e5f25b1b396b14242a6bb0508e2) 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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