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CVE-2026-93787

Vulnérabilité élevée dans Linux (Linux)

CVSS 8.1 · Élevée
EPSS 0.3%
Linux•Linux•Versions : <=6.1.*, <cf87ef1e62ed31a439064cef69d6eec38c68bd92, <=6.12.*, 2.6.12, <03003506c86f90312b0966283662c42fcab66e4b, <4cb3d79beee0fecc739ce07af915d503f29ae557, 6.18.53, 0, <2.6.12, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 6.6.158, <=6.6.*, 6.1.189, <=6.18.*, <=*, <6e3b965267b7313903baba2739992b1e2e92d540, <f8cf09a53a0dc1da298e9dd0ba5f21710cf119d6, 7.2, 6.12.111

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: bound dirent name against end of SMB response in cifs_filldir cifs_filldir() copies the entry name out of an SMB1 TRANS2_FIND_FIRST / FIND_NEXT response using a length (de.namelen) supplied by the server. The kmalloc'd SMB response buffer is bounded, but nothing checks that de.name + de.namelen still lies inside that buffer before the eventual filldir64() -> verify_dirent_name() -> memchr() reads namelen bytes. A hostile SMB1 server that returns an oversized FileNameLength in a directory entry therefore causes memchr() to read past the end of the response slab buffer. Reachable from any user who can list a directory on a CIFS mount served by an attacker-controlled server (getdents64() on the mounted directory): BUG: KASAN: slab-out-of-bounds in memchr+0x71/0x80 Read of size 1 at addr ffff88800e0640cc by task poc/115 Call Trace: dump_stack_lvl+0x64/0x80 print_report+0xce/0x620 kasan_report+0xec/0x120 memchr+0x71/0x80 filldir64+0x4c/0x6a0 cifs_filldir.constprop.0+0x9bb/0x1e00 cifs_readdir+0x2101/0x3380 iterate_dir+0x19c/0x520 __x64_sys_getdents64+0x126/0x210 do_syscall_64+0x107/0x5a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f Pass the end-of-response pointer down to cifs_filldir() and reject entries whose name would extend past that boundary. This bug was discovered by Artiphishell's vTriage pipeline, which generated a userspace reproducer (an emulated hostile SMB1 server plus a getdents64() client) that reliably triggers the KASAN report on an unpatched kernel. The fix below was drafted with the Claude coding assistant; a userspace reproducer is available on request.

Gravité et risque d'exploitation

CVE-2026-93787 obtient un score CVSS de 8.1/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.34 %, ce qui la place devant 26.4 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <=6.1.*, <cf87ef1e62ed31a439064cef69d6eec38c68bd92, <=6.12.*, 2.6.12, <03003506c86f90312b0966283662c42fcab66e4b, <4cb3d79beee0fecc739ce07af915d503f29ae557, 6.18.53, 0, <2.6.12, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 6.6.158, <=6.6.*, 6.1.189, <=6.18.*, <=*, <6e3b965267b7313903baba2739992b1e2e92d540, <f8cf09a53a0dc1da298e9dd0ba5f21710cf119d6, 7.2, 6.12.111) 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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