CVE-2026-93191
smack: fix incorrect task context in smack_msg_queue_msgrcv
Published Sep 17, 2026
CVSS n/a
EPSS < 1%
KEV · Not listed
Description
In the Linux kernel, the following vulnerability has been resolved:
smack: fix incorrect task context in smack_msg_queue_msgrcv
The smack_msg_queue_msgrcv() function incorrectly checks
the permissions of the 'current' task instead of the
'target' task.
In the msgsnd() syscall path, if a receiver is already waiting,
the pipelined_send() optimization is used to push the message
directly to the receiver task:
ipc/msg.c`pipelined_send():
` smp_store_release(&msr->r_msg, msg)
In this case, the 'sender' (current) task performs the check
on behalf of the 'receiver' task (msr->r_tsk, passed as the
'target' parameter):
ipc/msg.c`pipelined_send():
` security_msg_queue_msgrcv(,, target := msr->r_tsk,,)
However, smack_msg_queue_msgrcv() ignores the 'target' and
checks 'current':
smack_msg_queue_msgrcv(…)
` smk_curacc_msq(isp, MAY_READWRITE); // current task
'current' MAY satisfy smack_msg_queue_msgrcv r/w requirement,
but 'target' (the receiver task) might NOT;
as a result, an unauthorized receiver gets the message,
violating MAC policy.
Test:
1) create a sysv message queue with label “foo”
2) echo "bar foo r" >/smack/load2
3) msgrcv(,,,0,MSG_NOERROR) in "bar"-labeled task.
The task is waiting for the messages ...
4) msgsnd() from a "foo"-labeled task:
"bar"-labeled task gets the message.
This patch fixes the issue by checking permission on the
'target' task instead of 'current'.
(2008-02-04, Casey Schaufler)
smack: fix incorrect task context in smack_msg_queue_msgrcv
The smack_msg_queue_msgrcv() function incorrectly checks
the permissions of the 'current' task instead of the
'target' task.
In the msgsnd() syscall path, if a receiver is already waiting,
the pipelined_send() optimization is used to push the message
directly to the receiver task:
ipc/msg.c`pipelined_send():
` smp_store_release(&msr->r_msg, msg)
In this case, the 'sender' (current) task performs the check
on behalf of the 'receiver' task (msr->r_tsk, passed as the
'target' parameter):
ipc/msg.c`pipelined_send():
` security_msg_queue_msgrcv(,, target := msr->r_tsk,,)
However, smack_msg_queue_msgrcv() ignores the 'target' and
checks 'current':
smack_msg_queue_msgrcv(…)
` smk_curacc_msq(isp, MAY_READWRITE); // current task
'current' MAY satisfy smack_msg_queue_msgrcv r/w requirement,
but 'target' (the receiver task) might NOT;
as a result, an unauthorized receiver gets the message,
violating MAC policy.
Test:
1) create a sysv message queue with label “foo”
2) echo "bar foo r" >/smack/load2
3) msgrcv(,,,0,MSG_NOERROR) in "bar"-labeled task.
The task is waiting for the messages ...
4) msgsnd() from a "foo"-labeled task:
"bar"-labeled task gets the message.
This patch fixes the issue by checking permission on the
'target' task instead of 'current'.
(2008-02-04, Casey Schaufler)
Affected Products
-
CVE record
-
NVD configurations
No data
-
Red Hat packages
No data
-
OpenCVE enrichment
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||||||||||||||
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| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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No data.
No data.
| Vendor | Product | Versions | ||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux Kernel |
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| Linux | Linux Kernel |
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Remediation
Tracking
Advisories
| Source | ID | Title |
|---|---|---|
 Debian DLA |
DLA-4817-1 | linux-6.12 security update |
| Debian DLA |
DLA-4841-1 | linux security update |
 Debian DSA |
DSA-6528-1 | linux security update |
 Ubuntu USN |
USN-8961-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-9019-1 | Linux kernel (Azure) vulnerabilities |
| Ubuntu USN |
USN-9020-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-9022-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-9023-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-9024-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-9025-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-9026-1 | Linux kernel (Azure) vulnerabilities |
| Ubuntu USN |
USN-9029-1 | Linux kernel (Raspberry Pi) vulnerabilities |
| Ubuntu USN |
USN-9039-1 | Linux kernel (Azure CVM) vulnerabilities |
| Ubuntu USN |
USN-9040-1 | Linux kernel (Low Latency NVIDIA) vulnerabilities |
| Ubuntu USN |
USN-9066-1 | Linux kernel (HWE) vulnerabilities |
| Ubuntu USN |
USN-9091-1 | Linux kernel (NVIDIA Tegra) vulnerabilities |
Metrics
No CVSS v4.0
No CVSS v3.1
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.196% probability within 30 days)
Key SSVC decision points have not yet been added.
References
History
Sep 19, 2026 9:45 AM
Weaknesses updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-284 |
Sep 17, 2026 4:30 PM
Description updated. Title updated. First appearance in the feed. Affected versions updated. Affected vendors updated. Added references
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: smack: fix incorrect task context in smack_msg_queue_msgrcv The smack_msg_queue_msgrcv() function incorrectly checks the permissions of the 'current' task instead of the 'target' task. In the msgsnd() syscall path, if a receiver is already waiting, the pipelined_send() optimization is used to push the message directly to the receiver task: ipc/msg.c`pipelined_send(): ` smp_store_release(&msr->r_msg, msg) In this case, the 'sender' (current) task performs the check on behalf of the 'receiver' task (msr->r_tsk, passed as the 'target' parameter): ipc/msg.c`pipelined_send(): ` security_msg_queue_msgrcv(,, target := msr->r_tsk,,) However, smack_msg_queue_msgrcv() ignores the 'target' and checks 'current': smack_msg_queue_msgrcv(…) ` smk_curacc_msq(isp, MAY_READWRITE); // current task 'current' MAY satisfy smack_msg_queue_msgrcv r/w requirement, but 'target' (the receiver task) might NOT; as a result, an unauthorized receiver gets the message, violating MAC policy. Test: 1) create a sysv message queue with label “foo” 2) echo "bar foo r" >/smack/load2 3) msgrcv(,,,0,MSG_NOERROR) in "bar"-labeled task. The task is waiting for the messages ... 4) msgsnd() from a "foo"-labeled task: "bar"-labeled task gets the message. This patch fixes the issue by checking permission on the 'target' task instead of 'current'. (2008-02-04, Casey Schaufler) | |
| Title | smack: fix incorrect task context in smack_msg_queue_msgrcv | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
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Subscriptions
Weaknesses
