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CVE-2025-40323

Vulnérabilité élevée dans Linux (Linux)

CVSS 7.8 · Élevée
EPSS 0.1%
Linux•Linux•Versions : <=6.1.*, <4ac18f0e6a6d599ca751c4cd98e522afc8e3d4eb, <=6.12.*, 2.6.12, <a1f3058930745d2b938b6b4f5bd9630dc74b26b7, 6.17.8, 0, <2.6.12, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 6.18, <=6.6.*, <468f78276a37f4c6499385a4ce28f4f57be6655d, 5.15.203, <c079d42f70109512eee49123a843be91d8fa133f, <39c2c1a2773aaf73e56906e5ef670114eb2d354f, 6.6.117, 6.1.159, 6.12.58, <=*, <=5.15.*, <=6.17.*, <de89d19f4f30d9a8de87b9d08c1bd35cb70576d8

Description

In the Linux kernel, the following vulnerability has been resolved: fbcon: Set fb_display[i]->mode to NULL when the mode is released Recently, we discovered the following issue through syzkaller: BUG: KASAN: slab-use-after-free in fb_mode_is_equal+0x285/0x2f0 Read of size 4 at addr ff11000001b3c69c by task syz.xxx ... Call Trace: <TASK> dump_stack_lvl+0xab/0xe0 print_address_description.constprop.0+0x2c/0x390 print_report+0xb9/0x280 kasan_report+0xb8/0xf0 fb_mode_is_equal+0x285/0x2f0 fbcon_mode_deleted+0x129/0x180 fb_set_var+0xe7f/0x11d0 do_fb_ioctl+0x6a0/0x750 fb_ioctl+0xe0/0x140 __x64_sys_ioctl+0x193/0x210 do_syscall_64+0x5f/0x9c0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Based on experimentation and analysis, during framebuffer unregistration, only the memory of fb_info->modelist is freed, without setting the corresponding fb_display[i]->mode to NULL for the freed modes. This leads to UAF issues during subsequent accesses. Here's an example of reproduction steps: 1. With /dev/fb0 already registered in the system, load a kernel module to register a new device /dev/fb1; 2. Set fb1's mode to the global fb_display[] array (via FBIOPUT_CON2FBMAP); 3. Switch console from fb to VGA (to allow normal rmmod of the ko); 4. Unload the kernel module, at this point fb1's modelist is freed, leaving a wild pointer in fb_display[]; 5. Trigger the bug via system calls through fb0 attempting to delete a mode from fb0. Add a check in do_unregister_framebuffer(): if the mode to be freed exists in fb_display[], set the corresponding mode pointer to NULL.

Gravité et risque d'exploitation

CVE-2025-40323 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 0.14 %, ce qui la place devant 3.0 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <=6.1.*, <4ac18f0e6a6d599ca751c4cd98e522afc8e3d4eb, <=6.12.*, 2.6.12, <a1f3058930745d2b938b6b4f5bd9630dc74b26b7, 6.17.8, 0, <2.6.12, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 6.18, <=6.6.*, <468f78276a37f4c6499385a4ce28f4f57be6655d, 5.15.203, <c079d42f70109512eee49123a843be91d8fa133f, <39c2c1a2773aaf73e56906e5ef670114eb2d354f, 6.6.117, 6.1.159, 6.12.58, <=*, <=5.15.*, <=6.17.*, <de89d19f4f30d9a8de87b9d08c1bd35cb70576d8) 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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