CVE-2026-23238

Description

In the Linux kernel, the following vulnerability has been resolved: romfs: check sb_set_blocksize() return value romfs_fill_super() ignores the return value of sb_set_blocksize(), which can fail if the requested block size is incompatible with the block device's configuration. This can be triggered by setting a loop device's block size larger than PAGE_SIZE using ioctl(LOOP_SET_BLOCK_SIZE, 32768), then mounting a romfs filesystem on that device. When sb_set_blocksize(sb, ROMBSIZE) is called with ROMBSIZE=4096 but the device has logical_block_size=32768, bdev_validate_blocksize() fails because the requested size is smaller than the device's logical block size. sb_set_blocksize() returns 0 (failure), but romfs ignores this and continues mounting. The superblock's block size remains at the device's logical block size (32768). Later, when sb_bread() attempts I/O with this oversized block size, it triggers a kernel BUG in folio_set_bh(): kernel BUG at fs/buffer.c:1582! BUG_ON(size > PAGE_SIZE); Fix by checking the return value of sb_set_blocksize() and failing the mount with -EINVAL if it returns 0.

Gravité et risque d'exploitation

CVE-2026-23238 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 0.20 %, ce qui la place devant 8.8 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <cbd9931e6456822067725354d83446c5bb813030, <=6.1.*, <=6.12.*, 5.15.201, 6.12.74, 2.6.12, 6.1.164, 6.18.13, 0, <2.6.12, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, <=5.10.*, <ab7ad7abb3660c58ffffdf07ff3bb976e7e0afa0, <=6.6.*, <a381f0f61b35c8894b0bd0d6acef2d8f9b08b244, <f2521ab1f63a8c244f06a080319e5ff9a2e1bd95, <=6.18.*, <4b71ad7676564a94ec5f7d18298f51e8ae53db73, <9b203b8ddd7359270e8a694d0584743555128e2c, <2c5829cd8fbbc91568c520b666898f57cdcb8cf6, <=*, <=5.15.*, 6.19, 6.6.127, 5.10.251) 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/a381f0f61b35c8894b0bd0d6acef2d8f9b08b244
• https://git.kernel.org/stable/c/f2521ab1f63a8c244f06a080319e5ff9a2e1bd95
• https://git.kernel.org/stable/c/2c5829cd8fbbc91568c520b666898f57cdcb8cf6
• https://git.kernel.org/stable/c/cbd9931e6456822067725354d83446c5bb813030
• https://git.kernel.org/stable/c/9b203b8ddd7359270e8a694d0584743555128e2c
• https://git.kernel.org/stable/c/4b71ad7676564a94ec5f7d18298f51e8ae53db73
• https://git.kernel.org/stable/c/ab7ad7abb3660c58ffffdf07ff3bb976e7e0afa0