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CVE-2026-43472

Vulnérabilité non évaluée dans Linux (Linux)

CVSS 0.0 · Non évaluée
EPSS 0.1%
Linux•Linux•Versions : 741a295130606143edbf9fc740f633dbc1e6225f, <=6.1.*, <=6.12.*, 6.12.78, <845bf3c6963a52096d0d3866e4a92db77a0c03d8, 0, 7.0, <d7963d6997fea86a6def242ac36198b86655f912, 6.18.19, <=5.10.*, <=6.6.*, <=6.19.*, 2.6.16, 5.15.203, 6.19.9, <=6.18.*, 6.1.167, <aa9ebc084505fb26dd90f4d7a249045aad152043, <d0d99f60538ddb4a62ccaac2168d8f448965f083, <d3ffc8f13034af895531a02c30b1fe3a34b46432, <=*, <6c4b2243cb6c0755159bd567130d5e12e7b10d9f, 5.10.253, <=5.15.*, <af8f4be3b68ac8caa41c8e5ead0eeaf5e85e42d0, <2.6.16, 6.6.130, <42e21e74061b0ebbd859839f81acf10efad02a27

Description

In the Linux kernel, the following vulnerability has been resolved: unshare: fix unshare_fs() handling There's an unpleasant corner case in unshare(2), when we have a CLONE_NEWNS in flags and current->fs hadn't been shared at all; in that case copy_mnt_ns() gets passed current->fs instead of a private copy, which causes interesting warts in proof of correctness] > I guess if private means fs->users == 1, the condition could still be true. Unfortunately, it's worse than just a convoluted proof of correctness. Consider the case when we have CLONE_NEWCGROUP in addition to CLONE_NEWNS (and current->fs->users == 1). We pass current->fs to copy_mnt_ns(), all right. Suppose it succeeds and flips current->fs->{pwd,root} to corresponding locations in the new namespace. Now we proceed to copy_cgroup_ns(), which fails (e.g. with -ENOMEM). We call put_mnt_ns() on the namespace created by copy_mnt_ns(), it's destroyed and its mount tree is dissolved, but... current->fs->root and current->fs->pwd are both left pointing to now detached mounts. They are pinning those, so it's not a UAF, but it leaves the calling process with unshare(2) failing with -ENOMEM _and_ leaving it with pwd and root on detached isolated mounts. The last part is clearly a bug. There is other fun related to that mess (races with pivot_root(), including the one between pivot_root() and fork(), of all things), but this one is easy to isolate and fix - treat CLONE_NEWNS as "allocate a new fs_struct even if it hadn't been shared in the first place". Sure, we could go for something like "if both CLONE_NEWNS *and* one of the things that might end up failing after copy_mnt_ns() call in create_new_namespaces() are set, force allocation of new fs_struct", but let's keep it simple - the cost of copy_fs_struct() is trivial. Another benefit is that copy_mnt_ns() with CLONE_NEWNS *always* gets a freshly allocated fs_struct, yet to be attached to anything. That seriously simplifies the analysis... FWIW, that bug had been there since the introduction of unshare(2) ;-/

Gravité et risque d'exploitation

CVE-2026-43472 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 0.11 %, ce qui la place devant 1.4 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions 741a295130606143edbf9fc740f633dbc1e6225f, <=6.1.*, <=6.12.*, 6.12.78, <845bf3c6963a52096d0d3866e4a92db77a0c03d8, 0, 7.0, <d7963d6997fea86a6def242ac36198b86655f912, 6.18.19, <=5.10.*, <=6.6.*, <=6.19.*, 2.6.16, 5.15.203, 6.19.9, <=6.18.*, 6.1.167, <aa9ebc084505fb26dd90f4d7a249045aad152043, <d0d99f60538ddb4a62ccaac2168d8f448965f083, <d3ffc8f13034af895531a02c30b1fe3a34b46432, <=*, <6c4b2243cb6c0755159bd567130d5e12e7b10d9f, 5.10.253, <=5.15.*, <af8f4be3b68ac8caa41c8e5ead0eeaf5e85e42d0, <2.6.16, 6.6.130, <42e21e74061b0ebbd859839f81acf10efad02a27) 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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