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CVE-2026-93191

Vulnerability in Linux kernel (CVE-2026-93191)

Summary

Vulnerability in Linux kernel (CVE-2026-93191). Risk of unauthorized operations or information disclosure.

Original description

The description as published by the source.

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.cpipelined_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)

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-93191 has been found in Linux kernel.
Risk of unauthorized operations or information disclosure.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-93191" on the vendor's site.

CVE-2026-93191 (Linux kernel)
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (unclassified) exists in Linux kernel.

📍 Affected scope

Check the vendor advisory for the affected versions of Linux kernel.

🔥 Severity

Severity: ?. Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    Audit SBOM/dependencies for affected components.

    資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。

  2. 2
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

References

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