CVE-2026-74619 (GCVE-0-2026-74619)
Vulnerability from cvelistv5
Published
2026-08-22 15:32
Modified
2026-08-22 15:32
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
ovl: don't warn when the mount is completed from another user namespace
fsopen() records the caller's user namespace in fc->user_ns and hands
back an ordinary file descriptor. Nothing ties the task that calls
fsconfig(FSCONFIG_CMD_CREATE) to the task that created the context. The
fd is inherited across fork() and exec() and it can be passed over a
unix socket.
Completing a context from another user namespace is allowed on purpose.
vfs_cmd_create() authorizes the create with mount_capable(), which for
FS_USERNS_MOUNT checks ns_capable(fc->user_ns, CAP_SYS_ADMIN), and that
succeeds for a task holding CAP_SYS_ADMIN in an ancestor of fc->user_ns.
So an unprivileged task can reach the WARN_ON() in ovl_fill_super():
create a user and a mount namespace in a child, call fsopen("overlay")
there, send the fscontext fd to the parent and let the parent issue
FSCONFIG_CMD_CREATE. Both namespaces come from a plain unshare(1) and no
capability is needed anywhere:
WARNING: fs/overlayfs/super.c:1551 at ovl_fill_super+0x7b9/0x1e20 [overlay]
CPU: 3 UID: 1000 PID: 3243376 Comm: fswarn
Call Trace:
get_tree_nodev+0x71/0xa0
ovl_get_tree+0x15/0x20 [overlay]
vfs_get_tree+0x2a/0x100
vfs_cmd_create+0x60/0xf0
__do_sys_fsconfig+0x4b2/0x500
The child needs the mount namespace because fsopen() itself gates on
may_mount(), which asks for CAP_SYS_ADMIN in the user namespace owning
the caller's mount namespace. fsconfig() doesn't repeat that check.
It is a WARN_ON() and not a WARN_ON_ONCE(), so the condition can be
raised in a loop to taint the kernel and flood the log, and it panics a
kernel booted with panic_on_warn.
Keep refusing the mount and stop warning about it. ovl_parse_param()
already spells a user namespace check this way for Opt_override_creds.
References
Impacted products
{
"containers": {
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"programFiles": [
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"programFiles": [
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],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.5"
},
{
"lessThan": "6.5",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "6.6.152",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.104",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.45",
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{
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"status": "unaffected",
"version": "7.1.9",
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},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
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}
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"cpeApplicability": [
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"nodes": [
{
"cpeMatch": [
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"vulnerable": true
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{
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{
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{
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}
],
"negate": false,
"operator": "OR"
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}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\novl: don\u0027t warn when the mount is completed from another user namespace\n\nfsopen() records the caller\u0027s user namespace in fc-\u003euser_ns and hands\nback an ordinary file descriptor. Nothing ties the task that calls\nfsconfig(FSCONFIG_CMD_CREATE) to the task that created the context. The\nfd is inherited across fork() and exec() and it can be passed over a\nunix socket.\n\nCompleting a context from another user namespace is allowed on purpose.\nvfs_cmd_create() authorizes the create with mount_capable(), which for\nFS_USERNS_MOUNT checks ns_capable(fc-\u003euser_ns, CAP_SYS_ADMIN), and that\nsucceeds for a task holding CAP_SYS_ADMIN in an ancestor of fc-\u003euser_ns.\nSo an unprivileged task can reach the WARN_ON() in ovl_fill_super():\ncreate a user and a mount namespace in a child, call fsopen(\"overlay\")\nthere, send the fscontext fd to the parent and let the parent issue\nFSCONFIG_CMD_CREATE. Both namespaces come from a plain unshare(1) and no\ncapability is needed anywhere:\n\n WARNING: fs/overlayfs/super.c:1551 at ovl_fill_super+0x7b9/0x1e20 [overlay]\n CPU: 3 UID: 1000 PID: 3243376 Comm: fswarn\n Call Trace:\n get_tree_nodev+0x71/0xa0\n ovl_get_tree+0x15/0x20 [overlay]\n vfs_get_tree+0x2a/0x100\n vfs_cmd_create+0x60/0xf0\n __do_sys_fsconfig+0x4b2/0x500\n\nThe child needs the mount namespace because fsopen() itself gates on\nmay_mount(), which asks for CAP_SYS_ADMIN in the user namespace owning\nthe caller\u0027s mount namespace. fsconfig() doesn\u0027t repeat that check.\n\nIt is a WARN_ON() and not a WARN_ON_ONCE(), so the condition can be\nraised in a loop to taint the kernel and flood the log, and it panics a\nkernel booted with panic_on_warn.\n\nKeep refusing the mount and stop warning about it. ovl_parse_param()\nalready spells a user namespace check this way for Opt_override_creds."
}
],
"providerMetadata": {
"dateUpdated": "2026-08-22T15:32:03.511Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/513478092966dc9818d96dd2b3ed613fd2f6e30e"
},
{
"url": "https://git.kernel.org/stable/c/494346f2aab2489d379d43ff614aea447cf4e94d"
},
{
"url": "https://git.kernel.org/stable/c/be161fa31e3e9cc828a3c1bd935edca461e8a7a1"
},
{
"url": "https://git.kernel.org/stable/c/42d99fcd8006007e2f708bede6789f37f3910b30"
},
{
"url": "https://git.kernel.org/stable/c/63981fc786daaa626cb14d9be1406f674d79f98f"
}
],
"title": "ovl: don\u0027t warn when the mount is completed from another user namespace",
"x_generator": {
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}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74619",
"datePublished": "2026-08-22T15:32:03.511Z",
"dateReserved": "2026-08-15T05:44:03.921Z",
"dateUpdated": "2026-08-22T15:32:03.511Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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