CVE-2026-63830

Description

In the Linux kernel, the following vulnerability has been resolved: net: skmsg: preserve sg.copy across SG transforms The sk_msg sg.copy bitmap is part of the scatterlist entry ownership state. A set bit tells sk_msg_compute_data_pointers() not to expose the entry through writable BPF ctx->data. This protects entries backed by pages that are not private to the sk_msg, such as splice-backed file page-cache pages. Several sk_msg transform paths move, copy, split, or compact msg->sg.data[] entries without moving the matching sg.copy bit. This can make an externally backed entry arrive at a new slot with a clear copy bit. A later SK_MSG verdict can then expose sg_virt(sge) as writable ctx->data and BPF stores can modify the original page cache. Keep sg.copy synchronized with sg.data[] whenever entries are transferred, shifted, split, or copied into a new sk_msg. Clear the bit when an entry is replaced by a newly allocated private page or freed. This covers the BPF pull/push/pop helpers, sk_msg_shift_left/right(), sk_msg_xfer(), and tls_split_open_record(), including the partial tail entry created during TLS open-record splitting.

Gravité et risque d'exploitation

CVE-2026-63830 obtient un score CVSS de 9.4/10, soit une gravité critique. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.37 %, ce qui la place devant 29.7 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.1.*, <=6.12.*, 6.6.144, 4.20, 0, <=7.1.*, <1acdd14c0990dd1cd4b6534f00366d2e6dfce05f, d3b18ad31f93d0b6bae105c679018a1ba7daa9ca, <4.20, <31a110642b5fb5e61940cbcfb503445ac4f28017, <=5.10.*, <=6.6.*, 6.12.95, <406e8a651a7b854c41fecd5117bb282b3a6c2c6b, <f126eed589eec6f201405abbc398844042ef6d57, <0eb4c16c4adb262763bda870a8ed38a1a9dec7ec, <=6.18.*, 5.15.212, <21ed9540a8e1906dfcbc1bb82ba9b4de4fa4bd6d, 5.10.261, 6.1.177, 6.18.38, <=*, <=5.15.*, 7.1.3, 7.2, <d22cc92bc41290e5783a72375e0843d9435f6001, <9bb86d8184b37503816150c4a6ad3c17dfdbe827) 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/f126eed589eec6f201405abbc398844042ef6d57
• https://git.kernel.org/stable/c/31a110642b5fb5e61940cbcfb503445ac4f28017
• https://git.kernel.org/stable/c/9bb86d8184b37503816150c4a6ad3c17dfdbe827
• https://git.kernel.org/stable/c/0eb4c16c4adb262763bda870a8ed38a1a9dec7ec
• https://git.kernel.org/stable/c/d22cc92bc41290e5783a72375e0843d9435f6001
• https://git.kernel.org/stable/c/1acdd14c0990dd1cd4b6534f00366d2e6dfce05f
• https://git.kernel.org/stable/c/21ed9540a8e1906dfcbc1bb82ba9b4de4fa4bd6d
• https://git.kernel.org/stable/c/406e8a651a7b854c41fecd5117bb282b3a6c2c6b