fuse: check for NULL root inode in fuse_fill_super_submount
In the Linux kernel, the following vulnerability has been resolved: fuse: check for NULL root inode in fuse_fill_super_submount fuse_iget() can return NULL when its inode allocation fails, but fuse_fill_super_submount() passed the result straight to get_fuse_inode() and decremented fi->nlookup without checking it: root = fuse_iget(sb, parent_fi->nodeid, ...); fi = get_fuse_inode(root); fi->nlookup--; Inside fuse_iget() the inode allocation can fail and return NULL. The submount root takes the iget5_locked() path, whose alloc_inode() can fail under memory pressure (the auto-submount branch can fail the same way in new_inode() or fuse_alloc_submount_lookup()): inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid); if (!inode) return NULL; A NULL root makes get_fuse_inode() a container_of() on NULL and the nlookup decrement a write to a bogus address, oopsing the mount. With CONFIG_KASAN the following null pointer dereference is reported when the root inode allocation of an auto-submount fails (e.g. under memory pressure): ================================================================== BUG: KASAN: null-ptr-deref in fuse_get_tree_submount+0x656/0x8b0 Read of size 8 at addr 00000000000002b0 by task ls/942 CPU: 0 PID: 942 Comm: ls Tainted: G W 6.6 #15 Call Trace: fuse_get_tree_submount+0x656/0x8b0 vfs_get_tree+0x48/0x140 fc_mount+0x13/0x50 fuse_dentry_automount+0x7a/0xb0 __traverse_mounts+0xca/0x330 step_into+0x339/0xac0 path_lookupat+0xc5/0x2f0 filename_looku
CVE-2026-90139
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-90139
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "1866d779d5d2abae59d304e809600ca3ca8d0071",
"lessThan": "17120c5bfb16808509ea18d7fab6027802d93eba",
"versionType": "git"
},
{
"status": "affected",
"version": "1866d779d5d2abae59d304e809600ca3ca8d0071",
"lessThan": "e0b7f2922f6bd4c23cbddb7d1fc2bada570d27d1",
"versionType": "git"
},
{
"status": "affected",
"version": "1866d779d5d2abae59d304e809600ca3ca8d0071",
"lessThan": "a5129155ca9fba40d77ff19ffead8244e88d6f9c",
"versionType": "git"
},
{
"status": "affected",
"version": "1866d779d5d2abae59d304e809600ca3ca8d0071",
"lessThan": "509f4a09bae7f03c87f67f053648874a5e177867",
"versionType": "git"
},
{
"status": "affected",
"version": "1866d779d5d2abae59d304e809600ca3ca8d0071",
"lessThan": "928f659a3e3650978a5b4829cc982324f72b474b",
"versionType": "git"
}
],
"programFiles": [
"fs/fuse/inode.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.10"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.10",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.157",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.110",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.52",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.6",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/fuse/inode.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-90139
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #36538 · Revision 1
- Added to Heist Feed
- Publisher date