CVE-2026-97971
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: nstree: check listing permission before taking a namespace reference legitimize_ns() takes a reference on the candidate namespace before may_list_ns() has decided whether the caller may see it. The __free(ns_put) cleanup on the denied path can drop the last reference to a mount namespace while we still hold the rcu read lock, and put_mnt_ns() may sleep there. This is the same problem commit 2ec2aff3c8e2 ("ns: make sure reference are dropped outside of rcu lock") fixed for the put_user() path. Neither ns_requested() nor may_list_ns() needs a reference, both only look at the namespace type and at the caller's own namespaces, so do the checks first and take the reference last. Splat: Voluntary context switch within RCU read-side critical section! WARNING: kernel/rcu/tree_plugin.h:332 at rcu_note_context_switch+0x238/0x2a0, CPU#5: a/3442 CPU: 5 UID: 1000 PID: 3442 Comm: a Not tainted 7.0.0-30-generic #30-Ubuntu PREEMPT(lazy) RIP: 0010:rcu_note_context_switch+0x238/0x2a0 Call Trace: <TASK> __schedule+0xcf/0x650 schedule+0x27/0x90 schedule_preempt_disabled+0x15/0x30 __mutex_lock.constprop.0+0x550/0xaf0 __mutex_lock_slowpath+0x13/0x20 mutex_lock+0x3b/0x50 exp_funnel_lock+0xb2/0x260 synchronize_rcu_expedited+0xe7/0x220 namespace_unlock+0x26a/0x320 put_mnt_ns+0xd3/0x120 mntns_put+0xe/0x20 do_listns+0x13e/0x560 __do_sys_listns+0x126/0x2d0 __x64_sys_listns+0x20/0x30 x64_sys_call+0x2366/0x2390 do_syscall_64+0x105/0x5a0 entry_SYSCALL_64_after_hwframe+0x76/0x7e </TASK>
View original CVE JSON
{
"id": "CVE-2026-97971",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-09-25T11:17:24.980",
"lastModified": "2026-10-19T10:17:48.477",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnstree: check listing permission before taking a namespace reference\n\nlegitimize_ns() takes a reference on the candidate namespace before\nmay_list_ns() has decided whether the caller may see it. The\n__free(ns_put) cleanup on the denied path can drop the last reference to a\nmount namespace while we still hold the rcu read lock, and put_mnt_ns()\nmay sleep there. This is the same problem commit 2ec2aff3c8e2 (\"ns: make\nsure reference are dropped outside of rcu lock\") fixed for the put_user()\npath. Neither ns_requested() nor may_list_ns() needs a reference, both\nonly look at the namespace type and at the caller's own namespaces, so do\nthe checks first and take the reference last.\n\nSplat:\n\n Voluntary context switch within RCU read-side critical section!\n WARNING: kernel/rcu/tree_plugin.h:332 at rcu_note_context_switch+0x238/0x2a0, CPU#5: a/3442\n CPU: 5 UID: 1000 PID: 3442 Comm: a Not tainted 7.0.0-30-generic #30-Ubuntu PREEMPT(lazy)\n RIP: 0010:rcu_note_context_switch+0x238/0x2a0\n Call Trace:\n <TASK>\n __schedule+0xcf/0x650\n schedule+0x27/0x90\n schedule_preempt_disabled+0x15/0x30\n __mutex_lock.constprop.0+0x550/0xaf0\n __mutex_lock_slowpath+0x13/0x20\n mutex_lock+0x3b/0x50\n exp_funnel_lock+0xb2/0x260\n synchronize_rcu_expedited+0xe7/0x220\n namespace_unlock+0x26a/0x320\n put_mnt_ns+0xd3/0x120\n mntns_put+0xe/0x20\n do_listns+0x13e/0x560\n __do_sys_listns+0x126/0x2d0\n __x64_sys_listns+0x20/0x30\n x64_sys_call+0x2366/0x2390\n do_syscall_64+0x105/0x5a0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n </TASK>"
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"kernel/nstree.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "76b6f5dfb3fda76fce1f9990d6fa58adc711122b",
"lessThan": "9e673bf5d88aa898e52cef5c87058c3fa845bc71",
"versionType": "git",
"status": "affected"
},
{
"version": "76b6f5dfb3fda76fce1f9990d6fa58adc711122b",
"lessThan": "56ea4e86832d8abe8930394473566c194d189f85",
"versionType": "git",
"status": "affected"
}
]
},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"kernel/nstree.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "6.19",
"status": "affected"
},
{
"version": "0",
"lessThan": "6.19",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.2.7",
"lessThanOrEqual": "7.2.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {
"cvssMetricV31": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary",
"cvssData": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"attackVector": "LOCAL",
"attackComplexity": "LOW",
"privilegesRequired": "LOW",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"availabilityImpact": "HIGH"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9
}
]
},
"references": [
{
"url": "https://git.kernel.org/stable/c/56ea4e86832d8abe8930394473566c194d189f85",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/9e673bf5d88aa898e52cef5c87058c3fa845bc71",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
]
}