EUVD-2026-39225
GHSA-22m3-g27g-5h2v
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Local access with low privileges suffices via socket API; no confidentiality or integrity impact; high availability loss from kworker exhaustion confirms A:H with unchanged scope.
Primary rating from NVD.
CVSS VectorNVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Lifecycle Timeline
5DescriptionNVD
In the Linux kernel, the following vulnerability has been resolved:
net/smc: fix sleep-inside-lock in __smc_setsockopt() causing local DoS
A logic flaw in __smc_setsockopt() allows a local unprivileged user to cause a Denial of Service (DoS) by holding the socket lock indefinitely.
The function __smc_setsockopt() calls copy_from_sockptr() while holding lock_sock(sk). By passing a userfaultfd-monitored memory page (or FUSE-backed memory on systems where unprivileged userfaultfd is disabled) as the optval, an attacker can halt execution during the copy operation, keeping the lock held.
Combined with asynchronous tear-down operations like shutdown(), this exhausts the kernel wq (kworkers) and triggers the hung task watchdog.
[ 240.123456] INFO: task kworker/u8:2 blocked for more than 120 seconds. [ 240.123489] Call Trace: [ 240.123501] smc_shutdown+... [ 240.123512] lock_sock_nested+...
This patch moves the user-space copy outside the lock_sock() critical section to prevent the issue.
AnalysisAI
Sleep-inside-lock in the Linux kernel's SMC networking subsystem (__smc_setsockopt()) allows a local low-privilege user to hold the socket lock indefinitely, exhausting kernel worker threads and triggering the hung task watchdog - producing a local denial of service. Affected systems must have the net/smc module loaded and a user-space mechanism (userfaultfd or FUSE) available to stall the in-kernel copy operation. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires a local shell account with the ability to open SMC sockets - meaning the `net/smc` kernel module must be loaded or auto-loadable on the target system. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, score 5.5) accurately captures the local, low-complexity, low-privilege denial-of-service profile with no confidentiality or integrity impact. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | A local unprivileged user on a multi-tenant Linux host opens an SMC socket and calls `setsockopt()` with an `optval` pointer backed by a userfaultfd-monitored memory page. The kernel's `copy_from_sockptr()` blocks inside `lock_sock()`, holding the socket lock indefinitely. … |
| Remediation | The primary fix is to upgrade to a patched Linux kernel: 6.1.176 or later for the 6.1.x LTS tree, 6.6.143 or later for the 6.6.x LTS tree, 6.12.94 or later for the 6.12.x tree, 6.18.36 or later for the 6.18.x tree, or 7.0.13/7.1 for the mainline tree. … Detailed patch versions, workarounds, and compensating controls in full report. |
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Same technique Denial Of Service
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External POC / Exploit Code
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