CVE-2026-72183 (GCVE-0-2026-72183)
Vulnerability from cvelistv5
Published
2026-08-15 05:53
Modified
2026-08-17 05:41
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
landlock: Fix LANDLOCK_SCOPE_SIGNAL bypass on the SIGIO path
LANDLOCK_SCOPE_SIGNAL must prevent a sandboxed process from signaling
processes outside its Landlock domain. It can be bypassed through the
asynchronous SIGIO delivery path.
A sandboxed process that owns any file or socket can arm it with
fcntl(fd, F_SETOWN, -pgid), fcntl(fd, F_SETSIG, SIGKILL) and O_ASYNC, so
that an I/O event makes the kernel deliver the chosen signal to the
whole process group. As the head of its process group's task list (the
default position right after fork()) that group can also hold the
non-sandboxed process that launched it, e.g. a supervisor or a security
monitor. The sandbox can thus kill or signal the processes
LANDLOCK_SCOPE_SIGNAL is meant to protect from it.
The scope is enforced in hook_file_send_sigiotask() against the Landlock
domain recorded at F_SETOWN time, not the live domain of the sender.
control_current_fowner() decides whether to record that domain and skips
recording it when the fowner target is in the caller's thread group,
which is safe only for a single-task target (PIDTYPE_PID, PIDTYPE_TGID).
For a process group (PIDTYPE_PGID) pid_task() returns only one member;
recording is skipped whenever that member shares the caller's thread
group, and hook_file_send_sigiotask() then lets the signal fan out to
the whole group unchecked.
Record the domain for every non single-process target so the scope is
enforced against each group member at delivery time.
That recording is necessary but not sufficient on its own: the kernel
signals a process group through its members' thread-group leaders, and
the leader of the registrant's own process can carry a different
Landlock domain than the sibling thread that armed the owner.
domain_is_scoped() would then deny that leader, even though commit
18eb75f3af40 ("landlock: Always allow signals between threads of the
same process") requires same-process delivery to be allowed.
hook_task_kill() avoids this by evaluating same_thread_group() live, per
recipient; the SIGIO path instead delegates the whole decision to a
single registration-time check, which a process-group fan-out cannot
honor.
So also record the registrant's thread group next to its domain and
exempt it at delivery: hook_file_send_sigiotask() allows the signal
whenever the recipient belongs to the registrant's own process,
restoring the same-process guarantee while keeping out-of-domain group
members blocked. The direct kill() path (hook_task_kill) already
evaluates the live domain and is unaffected.
[mic: Check pid_type earlier and improve comment, fix commit message,
fix comment formatting]
References
| URL | Tags | |
|---|---|---|
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 332facfa80751b80006c2f95b13c6d208ab0aee1 Version: 18eb75f3af40be1f0fc2025d4ff821711222a2fd Version: 18eb75f3af40be1f0fc2025d4ff821711222a2fd Version: 18eb75f3af40be1f0fc2025d4ff821711222a2fd Version: 6861348d863c0eaa4af67492d640a9644a829c59 Version: 0906a9685d7057aea982e970da3e1cf3e5aca68b Version: 6.12.24 ≤ Version: 6.13.12 ≤ Version: 6.14.3 ≤ |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"security/landlock/fs.c",
"security/landlock/fs.h",
"security/landlock/task.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
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"version": "332facfa80751b80006c2f95b13c6d208ab0aee1",
"versionType": "git"
},
{
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"version": "18eb75f3af40be1f0fc2025d4ff821711222a2fd",
"versionType": "git"
},
{
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"status": "affected",
"version": "18eb75f3af40be1f0fc2025d4ff821711222a2fd",
"versionType": "git"
},
{
"lessThan": "4b80320ca7ed03d6e683f95b6066565dc97b9f92",
"status": "affected",
"version": "18eb75f3af40be1f0fc2025d4ff821711222a2fd",
"versionType": "git"
},
{
"status": "affected",
"version": "6861348d863c0eaa4af67492d640a9644a829c59",
"versionType": "git"
},
{
"status": "affected",
"version": "0906a9685d7057aea982e970da3e1cf3e5aca68b",
"versionType": "git"
},
{
"lessThan": "6.12.101",
"status": "affected",
"version": "6.12.24",
"versionType": "semver"
},
{
"lessThan": "6.14",
"status": "affected",
"version": "6.13.12",
"versionType": "semver"
},
{
"lessThan": "6.15",
"status": "affected",
"version": "6.14.3",
"versionType": "semver"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"security/landlock/fs.c",
"security/landlock/fs.h",
"security/landlock/task.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.15"
},
{
"lessThan": "6.15",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.101",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.40",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.101",
"versionStartIncluding": "6.12.24",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.40",
"versionStartIncluding": "6.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.13.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.14.3",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlandlock: Fix LANDLOCK_SCOPE_SIGNAL bypass on the SIGIO path\n\nLANDLOCK_SCOPE_SIGNAL must prevent a sandboxed process from signaling\nprocesses outside its Landlock domain. It can be bypassed through the\nasynchronous SIGIO delivery path.\n\nA sandboxed process that owns any file or socket can arm it with\nfcntl(fd, F_SETOWN, -pgid), fcntl(fd, F_SETSIG, SIGKILL) and O_ASYNC, so\nthat an I/O event makes the kernel deliver the chosen signal to the\nwhole process group. As the head of its process group\u0027s task list (the\ndefault position right after fork()) that group can also hold the\nnon-sandboxed process that launched it, e.g. a supervisor or a security\nmonitor. The sandbox can thus kill or signal the processes\nLANDLOCK_SCOPE_SIGNAL is meant to protect from it.\n\nThe scope is enforced in hook_file_send_sigiotask() against the Landlock\ndomain recorded at F_SETOWN time, not the live domain of the sender.\ncontrol_current_fowner() decides whether to record that domain and skips\nrecording it when the fowner target is in the caller\u0027s thread group,\nwhich is safe only for a single-task target (PIDTYPE_PID, PIDTYPE_TGID).\nFor a process group (PIDTYPE_PGID) pid_task() returns only one member;\nrecording is skipped whenever that member shares the caller\u0027s thread\ngroup, and hook_file_send_sigiotask() then lets the signal fan out to\nthe whole group unchecked.\n\nRecord the domain for every non single-process target so the scope is\nenforced against each group member at delivery time.\n\nThat recording is necessary but not sufficient on its own: the kernel\nsignals a process group through its members\u0027 thread-group leaders, and\nthe leader of the registrant\u0027s own process can carry a different\nLandlock domain than the sibling thread that armed the owner.\ndomain_is_scoped() would then deny that leader, even though commit\n18eb75f3af40 (\"landlock: Always allow signals between threads of the\nsame process\") requires same-process delivery to be allowed.\nhook_task_kill() avoids this by evaluating same_thread_group() live, per\nrecipient; the SIGIO path instead delegates the whole decision to a\nsingle registration-time check, which a process-group fan-out cannot\nhonor.\n\nSo also record the registrant\u0027s thread group next to its domain and\nexempt it at delivery: hook_file_send_sigiotask() allows the signal\nwhenever the recipient belongs to the registrant\u0027s own process,\nrestoring the same-process guarantee while keeping out-of-domain group\nmembers blocked. The direct kill() path (hook_task_kill) already\nevaluates the live domain and is unaffected.\n\n[mic: Check pid_type earlier and improve comment, fix commit message,\nfix comment formatting]"
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 8.4,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - Exploitation requires local syscalls (fcntl F_SETOWN/F_SETSIG/F_SETFL, landlock_restrict_self, and pipe or socket I/O); the bug is in hook_file_send_sigiotask() on the SIGIO path with no network, Bluetooth, or physical entry point.\nAC:L - The attacker controls every step (fork into the launcher process group, apply LANDLOCK_SCOPE_SIGNAL, arm O_ASYNC with -pgid, trigger I/O); the upstream selftest reproduces the bypass deterministically with no race or layout dependency.\nPR:L - Only an ordinary local user running inside a Landlock sandbox with LANDLOCK_SCOPE_SIGNAL is needed; landlock_restrict_self() and fcntl() require no capabilities (selftests call drop_caps()), matching other Landlock CVE scoring.\nUI:N - The exploited supervisor or monitor is the attacker\u0027s own parent in the shared process group; escalation is driven entirely by the sandboxed process\u0027s syscalls with no separate victim interaction.\nS:C - This bypasses LANDLOCK_SCOPE_SIGNAL, letting a confined process signal or SIGKILL tasks outside its Landlock domain (e.g., the unsandboxed launcher), crossing the sandbox security authority like CVE-2024-42318.\nC:N - The flaw only skips signal-scope enforcement on asynchronous SIGIO delivery; it does not read kernel or victim memory or leak pointers, and no confidentiality primitive is created even with arbitrary signal choice.\nI:H - A sandboxed attacker can deliver arbitrary signals including SIGKILL to every out-of-domain process group member reachable via fcntl(F_SETOWN,-pgid)/O_ASYNC, completely defeating the integrity of LANDLOCK_SCOPE_SIGNAL protections.\nA:H - SIGKILL (explicitly shown in the fix commit) or other fatal/control signals terminate the supervisor, security monitor, or peer processes the policy was meant to isolate, causing high availability loss."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-17T05:41:13.731Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/7a92e9fd1d496a610b40e0c4253fd54e7496f5ab"
},
{
"url": "https://git.kernel.org/stable/c/1f18aac2637220b5847d073447498e81ddca10b2"
},
{
"url": "https://git.kernel.org/stable/c/04916f7dc6d37cd478b06c86398c34a6963ac8c9"
},
{
"url": "https://git.kernel.org/stable/c/4b80320ca7ed03d6e683f95b6066565dc97b9f92"
}
],
"title": "landlock: Fix LANDLOCK_SCOPE_SIGNAL bypass on the SIGIO path",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-72183",
"datePublished": "2026-08-15T05:53:45.922Z",
"dateReserved": "2026-08-09T03:40:39.910Z",
"dateUpdated": "2026-08-17T05:41:13.731Z",
"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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