CVE-2026-68179 misc: nsm: only unlock nsm_dev on post-lock error paths
A local attacker can trigger a kernel warning and potential instability by causing an invalid unlock of a mutex in the NSM driver via a specific ioctl call.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-68179?
CVE-2026-68179 is a high-severity vulnerability in Linux, published on 10 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Weakness: CWE-675
Which versions are affected by CVE-2026-68179?
How do I fix CVE-2026-68179?
Apply the vendor's patch.
Is CVE-2026-68179 being exploited?
There is no known exploitation of CVE-2026-68179 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-68179, DEBIAN-CVE-2026-68179, GHSA-3jf9-7qhv-4pm6, UBUNTU-CVE-2026-68179.