CVE-2026-63892

Description

In the Linux kernel, the following vulnerability has been resolved: thunderbolt: property: Reject dir_len < 4 to prevent size_t underflow On the non-root path, __tb_property_parse_dir() takes dir_len from entry->length (u16 widened to size_t). Two distinct OOB conditions follow when entry->length < 4: 1. The non-root path begins with kmemdup(&block[dir_offset], sizeof(*dir->uuid), ...) which always reads 4 dwords from dir_offset. tb_property_entry_valid() only enforces dir_offset + entry->length <= block_len, so a crafted entry with dir_offset close to the end of the property block and entry->length in 0..3 passes that gate but lets the UUID copy run off the block (e.g. dir_offset = 497, dir_len = 3 in a 500-dword block reads block[497..501]). 2. After the kmemdup, content_len = dir_len - 4 underflows size_t to ~SIZE_MAX, nentries becomes SIZE_MAX / 4, and the entry walk runs OOB on each iteration until an entry fails validation or the kernel oopses on an unmapped page. Reject dir_len < 4 on the non-root path *before* the UUID kmemdup, which closes both holes. Also move INIT_LIST_HEAD(&dir->properties) up to immediately after the dir allocation so the new error-return path (and the existing uuid-alloc failure path) calling tb_property_free_dir() sees a walkable list rather than the zero-initialized NULL next/prev that list_for_each_entry_safe() would oops on.

Gravité et risque d'exploitation

CVE-2026-63892 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.23 %, ce qui la place devant 12.9 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.1.*, <=7.0.*, <=6.12.*, 6.12.93, <542a13890b742099c461d70920e97b14e568f6ec, 0, 6.18.35, <37abc4504fa19d8f9f1e87792e8a2b8fdb308e40, 6.1.176, cdae7c07e3e3509eaabc18c1640a55dc5b99c179, 5.15.210, <=5.10.*, <=6.6.*, <d548179adcc87e1bc66b17e00352a1f536e76065, <3bec49ca55e08fb085cc4318f24b1b37eaab28cb, <de21b59c29e31c5108ddc04210631bbfab81b997, 7.1, <=6.18.*, <e2d4d51cf5785815fa4e91e0c019e3eb2506a84c, <de618299190b418291609e6921557253bd417e25, 7.0.12, <=*, <=5.15.*, 6.6.143, <4.15, <5506c825f14d810f0690b1f4367cb7249ebb387a, 4.15, 5.10.259) 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/37abc4504fa19d8f9f1e87792e8a2b8fdb308e40
• https://git.kernel.org/stable/c/e2d4d51cf5785815fa4e91e0c019e3eb2506a84c
• https://git.kernel.org/stable/c/de618299190b418291609e6921557253bd417e25
• https://git.kernel.org/stable/c/5506c825f14d810f0690b1f4367cb7249ebb387a
• https://git.kernel.org/stable/c/542a13890b742099c461d70920e97b14e568f6ec
• https://git.kernel.org/stable/c/d548179adcc87e1bc66b17e00352a1f536e76065
• https://git.kernel.org/stable/c/3bec49ca55e08fb085cc4318f24b1b37eaab28cb
• https://git.kernel.org/stable/c/de21b59c29e31c5108ddc04210631bbfab81b997