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CVE-2026-43472: Linux

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Вероятност да бъде експлоатирана в следващите 30 дни (EPSS)

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    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

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    • Linux Linux: 741a295130606143edbf9fc740f633dbc1e6225f преди 845bf3c6963a52096d0d3866e4a92db77a0c03d8; 741a295130606143edbf9fc740f633dbc1e6225f преди d3ffc8f13034af895531a02c30b1fe3a34b46432; 741a295130606143edbf9fc740f633dbc1e6225f преди d0d99f60538ddb4a62ccaac2168d8f448965f083; 741a295130606143edbf9fc740f633dbc1e6225f преди d7963d6997fea86a6def242ac36198b86655f912; 741a295130606143edbf9fc740f633dbc1e6225f преди aa9ebc084505fb26dd90f4d7a249045aad152043; 741a295130606143edbf9fc740f633dbc1e6225f преди af8f4be3b68ac8caa41c8e5ead0eeaf5e85e42d0; 741a295130606143edbf9fc740f633dbc1e6225f преди 42e21e74061b0ebbd859839f81acf10efad02a27; 741a295130606143edbf9fc740f633dbc1e6225f преди 6c4b2243cb6c0755159bd567130d5e12e7b10d9f
    • Linux Linux: 2.6.16; преди 2.6.16; 5.10.253 до 5.10.*; 5.15.203 до 5.15.*; 6.1.167 до 6.1.*; 6.6.130 до 6.6.*; 6.12.78 до 6.12.*; 6.18.19 до 6.18.*; 6.19.9 до 6.19.*; 7.0 до *

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    • 8 май 2026 Публикувано

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    CVE-2026-43472: Linux | freedomonline.bg