{"id":"CVE-2026-90139","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nfuse: check for NULL root inode in fuse_fill_super_submount\n\nfuse_iget() can return NULL when its inode allocation fails, but\nfuse_fill_super_submount() passed the resu…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nfuse: check for NULL root inode in fuse_fill_super_submount\n\nfuse_iget() can return NULL when its inode allocation fails, but\nfuse_fill_super_submount() passed the resu…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 1866d779d5d2abae59d304e809600ca3ca8d0071 < 17120c5bfb16808509ea18d7fab6027802d93eba","Linux >= 1866d779d5d2abae59d304e809600ca3ca8d0071 < e0b7f2922f6bd4c23cbddb7d1fc2bada570d27d1","Linux >= 1866d779d5d2abae59d304e809600ca3ca8d0071 < a5129155ca9fba40d77ff19ffead8244e88d6f9c","Linux >= 1866d779d5d2abae59d304e809600ca3ca8d0071 < 509f4a09bae7f03c87f67f053648874a5e177867","Linux >= 1866d779d5d2abae59d304e809600ca3ca8d0071 < 928f659a3e3650978a5b4829cc982324f72b474b","Linux 5.10"],"published":"2026-09-17","updated":"2026-09-17","sourceUpdated":"2026-09-17T17:17:06.523","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-90139","references":[{"url":"https://git.kernel.org/stable/c/17120c5bfb16808509ea18d7fab6027802d93eba","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/509f4a09bae7f03c87f67f053648874a5e177867","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/928f659a3e3650978a5b4829cc982324f72b474b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a5129155ca9fba40d77ff19ffead8244e88d6f9c","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e0b7f2922f6bd4c23cbddb7d1fc2bada570d27d1","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-09-17T16:21:47.878Z","epss":0.002,"epssPercentile":0.10158,"slug":"CVE-2026-90139","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nfuse: check for NULL root inode in fuse_fill_super_submount\n\nfuse_iget() can return NULL when its inode allocation fails, but\nfuse_fill_super_submount() passed the result straight to get_fuse_inode()\nand decremented fi->nlookup without checking it:\n\n        root = fuse_iget(sb, parent_fi->nodeid, ...);\n        fi = get_fuse_inode(root);\n        fi->nlookup--;\n\nInside fuse_iget() the inode allocation can fail and return NULL.  The\nsubmount root takes the iget5_locked() path, whose alloc_inode() can fail\nunder memory pressure (the auto-submount branch can fail the same way in\nnew_inode() or fuse_alloc_submount_lookup()):\n\n        inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set,\n                             &nodeid);\n        if (!inode)\n                return NULL;\n\nA NULL root makes get_fuse_inode() a container_of() on NULL and the\nnlookup decrement a write to a bogus address, oopsing the mount.  With\nCONFIG_KASAN the following null pointer dereference is reported when the\nroot inode allocation of an auto-submount fails (e.g. under memory\npressure):\n\n==================================================================\nBUG: KASAN: null-ptr-deref in fuse_get_tree_submount+0x656/0x8b0\nRead of size 8 at addr 00000000000002b0 by task ls/942\nCPU: 0 PID: 942 Comm: ls Tainted: G W 6.6 #15\nCall Trace:\n <TASK>\n fuse_get_tree_submount+0x656/0x8b0\n vfs_get_tree+0x48/0x140\n fc_mount+0x13/0x50\n fuse_dentry_automount+0x7a/0xb0\n __traverse_mounts+0xca/0x330\n step_into+0x339/0xac0\n path_lookupat+0xc5/0x2f0\n filename_lookup+0x163/0x2a0\n vfs_statx+0xd5/0x200\n do_statx+0x83/0xd0\n __x64_sys_statx+0xa0/0xc0\n do_syscall_64+0x37/0x90\n entry_SYSCALL_64_after_hwframe+0x78/0xe2\n </TASK>\n==================================================================\n\nReturn -ENOMEM instead; the caller tears down the partially built\nsuperblock on error, matching the other error returns in this\nfunction.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}