misc: nsm: only unlock nsm_dev on post-lock error paths
Key facts
- Attack vector
- Local
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA.
Summary
In the Linux kernel, the following vulnerability has been resolved: misc: nsm: only unlock nsm_dev on post-lock error paths nsm_dev_ioctl() jumps to the common out label even when the initial copy_from_user() fails before nsm->lock has been taken. The error path then blindly unlocks a mutex that was never acquired. This issue was found by our static analysis tool and then manually reviewed against the current tree. The grounded PoC kept the miscdevice ioctl entry and the pre-lock copy_from_user(&raw, argp, _IOC_SIZE(cmd)) failure path by issuing NSM_IOCTL_RAW with an invalid user pointer. That failure reaches the shared out label before mutex_lock(&nsm->lock). Lockdep reported: WARNING: bad unlock balance detected! exploit/193 is trying to release lock (&global_nsm.lock) at: nsm_dev_ioctl+0x5f/0xcf [vuln_msv] but there are no more locks to release! no locks held by exploit/193. Return immediately on the pre-lock copy_from_user() failure and keep the common unlock label for the post-lock paths only.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
- Fix · CNA Linux (Linux) Fixed in 6.12.101, 6.18.42, 7.1.6, 7.2
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
Not affected: 5 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2026-68179
- 2026-10-03 Alias added: GHSA-3jf9-7qhv-4pm6
- 2026-10-16 CISA SSVC decision points changed
- 2026-10-20 Weakness changed · CISA ADP
- 2026-11-07 Affected versions changed · Red Hat
- 2026-11-07 CVSS score added · Red Hat
References
More Linux vulnerabilities
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- TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
- TI-2021-02452 Incorrect authorization in Ubuntu linux kernel KEVCVSS 3.1HIGH 8.8
- TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
- TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
- TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
Sources
- CVE-2026-68179 · CVE Program
- CVE-2026-68179 · NVD
- FIRST EPSS
- GHSA-3jf9-7qhv-4pm6 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-68179 · Red Hat security data · CC BY 4.0
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