# CVE-2026-93191: smack: fix incorrect task context in smack_msg_queue_msgrcv

CVE-2026-93191 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-93191, released September 23, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-93191
- Priority: Routine
- CVSS: 3.3 (Low)
- EPSS: 0.0020
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 17, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-93191

## 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)

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 6.1.190-1 | [DEBIAN-CVE-2026-93191](https://patchblox.com/security/data/fix/linux/debian-cve-2026-93191.md) | Sep 23, 2026 |
| Linux | linux Debian 13.5 (trixie) | 6.12.111-1 | [DEBIAN-CVE-2026-93191](https://patchblox.com/security/data/fix/linux/debian-cve-2026-93191.md) | Sep 23, 2026 |
| Linux | linux Debian 14 | 7.2.6-1 | [DEBIAN-CVE-2026-93191](https://patchblox.com/security/data/fix/linux/debian-cve-2026-93191.md) | Sep 23, 2026 |
| Linux | linux-6.12 Debian 12.15 (bookworm) | 6.12.111-1~deb12u1 | [DEBIAN-CVE-2026-93191](https://patchblox.com/security/data/fix/linux/debian-cve-2026-93191.md) | Sep 23, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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