{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-68179", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-30T09:28:09.373Z", "datePublished": "2026-08-10T11:59:50.667Z", "dateUpdated": "2026-08-17T05:00:20.666Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:00:20.666Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmisc: nsm: only unlock nsm_dev on post-lock error paths\n\nnsm_dev_ioctl() jumps to the common out label even when the initial\ncopy_from_user() fails before nsm->lock has been taken. The error path\nthen blindly unlocks a mutex that was never acquired.\n\nThis issue was found by our static analysis tool and then manually\nreviewed against the current tree.\n\nThe grounded PoC kept the miscdevice ioctl entry and the pre-lock\ncopy_from_user(&raw, argp, _IOC_SIZE(cmd)) failure path by issuing\nNSM_IOCTL_RAW with an invalid user pointer. That failure reaches the\nshared out label before mutex_lock(&nsm->lock). Lockdep reported:\n\n WARNING: bad unlock balance detected!\n exploit/193 is trying to release lock (&global_nsm.lock) at:\n nsm_dev_ioctl+0x5f/0xcf [vuln_msv]\n but there are no more locks to release!\n no locks held by exploit/193.\n\nReturn immediately on the pre-lock copy_from_user() failure and keep the\ncommon unlock label for the post-lock paths only." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.4, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The flaw is reached only via the local ioctl syscall on /dev/nsm (open plus ioctl through vfs_ioctl to nsm_dev_ioctl); it is not exposed through any network protocol or remote service.\nAC:L - An attacker can reliably trigger the pre-lock copy_from_user failure with an invalid userspace pointer and can control the race by issuing concurrent ioctl or /dev/hwrng reads against the same nsm->lock.\nPR:N - The driver registers /dev/nsm as mode 0666 and performs no capability or permission checks in nsm_dev_ioctl, so any local process can open the device and issue NSM_IOCTL_RAW without elevated privileges.\nUI:N - Exploitation requires only the attacker issuing a crafted ioctl with an invalid argument pointer; no victim interaction, mounting, or other user action is needed.\nS:U - Impact is confined to corruption and privilege within the guest Nitro Enclave kernel; it does not cross into the hypervisor, parent instance, or another VM security boundary.\nC:H - Unlocking a mutex not held by the caller can clear owner while another context still holds nsm->lock, permitting concurrent unsynchronized access to shared nsm_msg buffers and virtio response data.\nI:H - Premature mutex release enables overlapping virtqueue operations and corruption of shared kernel message state, a memory-safety defect that can be leveraged for arbitrary kernel integrity compromise.\nA:H - The bug triggers lockdep bad-unlock warnings and kernel oops, and concurrent unsynchronized virtio access can panic, hang, or otherwise deny service to the enclave." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/misc/nsm.c" ], "versions": [ { "version": "b9873755a6c8ccfce79094c4dce9efa3ecb1a749", "lessThan": "4aa3f7d48e91eb74a363c1b4d7dbdd28f5b341fb", "status": "affected", "versionType": "git" }, { "version": "b9873755a6c8ccfce79094c4dce9efa3ecb1a749", "lessThan": "8f068342096b027181b168d91fef7ac7a2c64b25", "status": "affected", "versionType": "git" }, { "version": "b9873755a6c8ccfce79094c4dce9efa3ecb1a749", "lessThan": "f318f5a872cb9096536e759b23ae5c9873bb80ed", "status": "affected", "versionType": "git" }, { "version": "b9873755a6c8ccfce79094c4dce9efa3ecb1a749", "lessThan": "ce1fed11d18e163baf7f875152a33bf80f625c1a", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/misc/nsm.c" ], "versions": [ { "version": "6.8", "status": "affected" }, { "version": "0", "lessThan": "6.8", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.101", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.42", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.6", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.12.101" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.18.42" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "7.1.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/4aa3f7d48e91eb74a363c1b4d7dbdd28f5b341fb" }, { "url": "https://git.kernel.org/stable/c/8f068342096b027181b168d91fef7ac7a2c64b25" }, { "url": "https://git.kernel.org/stable/c/f318f5a872cb9096536e759b23ae5c9873bb80ed" }, { "url": "https://git.kernel.org/stable/c/ce1fed11d18e163baf7f875152a33bf80f625c1a" } ], "title": "misc: nsm: only unlock nsm_dev on post-lock error paths", "x_generator": { "engine": "bippy-1.2.0" } } } }