Patchlage

CVE-2026-72379

CVE CVE-2026-72379EUVD EUVD-2026-59278Published 2026-08-15T05:56:12.000ZLast changed 2026-08-17T05:13:31.000Z

What the advisory describes

In the Linux kernel, the following vulnerability has been resolved: fs: refuse O_TMPFILE creation with an unmapped fsuid or fsgid vfs_tmpfile() never checked that the caller's fsuid and fsgid map into the filesystem. On an idmapped mount whose idmapping does not cover the caller's fs{u,g}id, the ->tmpfile() instance initializes the new inode through inode_init_owner(), where mapped_fsuid()/mapped_fsgid() return INVALID_UID/INVALID_GID, and the tmpfile ends up owned by (uid_t)-1. Every other creation path already refuses this: may_o_create() (O_CREAT) and may_create_dentry() (mkdir, mknod, symlink, link) bail out with -EOVERFLOW via fsuidgid_has_mapping() precisely so that an object cannot be created with an owner the filesystem cannot represent. An O_TMPFILE is no exception: it is created I_LINKABLE and linkat(2) can splice it into the namespace afterwards, so the same guarantee must hold. Add the missing fsuidgid_has_mapping() check to vfs_tmpfile(). On a non-idmapped mount the caller's fs{u,g}id always map in the superblock's user namespace, so this is a no-op there and only takes effect on an idmapped mount that does not map the caller. It applies to every filesystem that sets FS_ALLOW_IDMAP and implements ->tmpfile() (tmpfs, ext4, btrfs, xfs, f2fs, ...), and to overlayfs, whose upper-layer tmpfile creation funnels through vfs_tmpfile() via backing_tmpfile_open().

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

An estate covering these products can be recorded in Patchlage. An advisory about them appears in the next morning's situation report.

Does this concern one of your customers?

This page cannot answer that — it does not know your estate. Whoever has recorded their environments gets the answer the morning after publication, together with a paragraph they can forward to the customer unedited.

Try it for 28 days

Patchlage reports hits and suspected hits. About everything else this system says nothing — neither this page nor the situation report ever claims that an estate is safe.