CVE-2026-97991

Description

In the Linux kernel, the following vulnerability has been resolved: vdpa_sim_blk: reject out-of-range sector starts vdpasim_blk_check_range() logs an invalid start sector but continues validating the request. The subsequent unsigned capacity subtraction can underflow and let an out-of-range buffer offset reach the data path. The invalid offset is used by three request paths. VIRTIO_BLK_T_OUT copies guest data to blk->buffer + offset through vringh_iov_pull_iotlb(), causing an out-of-bounds write in _copy_from_iter() or memcpy(). VIRTIO_BLK_T_IN copies from blk->buffer + offset to the guest through vringh_iov_push_iotlb(), causing an out-of-bounds read in _copy_to_iter(). VIRTIO_BLK_T_WRITE_ZEROES passes blk->buffer + offset to memset(), causing an out-of-bounds write. Reject starts at or beyond the capacity before the subtraction. Treat the capacity boundary as invalid because the IN and OUT paths round byte counts down to sectors for validation but later copy the original byte counts. A sub-sector request at the capacity boundary would otherwise still access past the end of the buffer. I found this bug myself, though the patch was written with AI assistance.

Gravité et risque d'exploitation

CVE-2026-97991 obtient un score CVSS de 7.8/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.12 %, ce qui la place devant 1.8 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.1.*, <=6.12.*, 7.2.7, <5.13, 6.18.53, <36ef4d8527f71648f00347f6ba759f0b7e5e0977, 0, <a8a1413a2cfdbedc896249f461d6d92efbbfe21f, 7d189f617f83f780915b737896a696ff605bd19f, <14acb0d44b7d90a077beb7b92b444b90bafda9d9, 6.6.158, <=6.6.*, <000c6300776ceaf6b715780113f4275b1be4195b, 6.1.189, <2ff2a8d063fdfa1e1479fb1fe2e3356a2ce89018, 5.13, <=6.18.*, 5.15.222, <=7.2.*, <d6dac17e20fd2abd0eb8c09d69fccf7426e12bcf, <=*, <=5.15.*, 6.12.111, <0a8693f00c408d85f086ad85d29e7030bf1e2055, 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

• https://git.kernel.org/stable/c/2ff2a8d063fdfa1e1479fb1fe2e3356a2ce89018
• https://git.kernel.org/stable/c/36ef4d8527f71648f00347f6ba759f0b7e5e0977
• https://git.kernel.org/stable/c/000c6300776ceaf6b715780113f4275b1be4195b
• https://git.kernel.org/stable/c/14acb0d44b7d90a077beb7b92b444b90bafda9d9
• https://git.kernel.org/stable/c/a8a1413a2cfdbedc896249f461d6d92efbbfe21f
• https://git.kernel.org/stable/c/d6dac17e20fd2abd0eb8c09d69fccf7426e12bcf
• https://git.kernel.org/stable/c/0a8693f00c408d85f086ad85d29e7030bf1e2055