CVE-2026-68438

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-68438", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-30T09:28:09.394Z", "datePublished": "2026-08-12T00:07:27.105Z", "dateUpdated": "2026-08-17T05:05:35.262Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:05:35.262Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmp: Make CSD lock acquisition atomic for debug mode\n\nCommit b0473dcd4b1d (\"smp: Improve smp_call_function_single()\nCSD-lock diagnostics\") changed smp_call_function_single() so that,\nwhen CSD lock debugging is enabled, async !wait calls use the\ndestination CPU csd_data. That improves diagnostics, but it also removes\nthe single-writer property that made the old csd_lock() safe: multiple\nCPUs can now prepare the same destination CPU CSD concurrently.\n\ncsd_lock() currently waits for CSD_FLAG_LOCK to clear and then sets the\nbit with a non-atomic read-modify-write. Two senders can both see an\nunlocked CSD, set the bit, overwrite the callback fields, and enqueue\nthe same llist node. Re-adding a node that is already the queue head can\nmake node->next point to itself, leaving the target CPU stuck walking\ncall_single_queue. Later synchronous work, such as a TLB shootdown, can\nthen remain queued and trigger soft-lockup warnings or panics.\n\nKeep the single csd_lock() implementation, but when CSD lock debugging is\nenabled, acquire CSD_FLAG_LOCK with try_cmpxchg_acquire(). This makes the\ndestination CPU CSD a real atomic lock in the only configuration where it\ncan be shared by multiple remote senders, while preserving the existing\nnon-debug fast path."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["kernel/smp.c"], "versions": [{"version": "b0473dcd4b1d7e2e44947e7ac1820c73a268821a", "lessThan": "282d220bae5fbfc90cf0e3d5b5e42c00ad79f989", "status": "affected", "versionType": "git"}, {"version": "b0473dcd4b1d7e2e44947e7ac1820c73a268821a", "lessThan": "35551efb155e3b83445a6c3f66cb498d5efc182c", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["kernel/smp.c"], "versions": [{"version": "7.1", "status": "affected"}, {"version": "0", "lessThan": "7.1", "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": "7.1", "versionEndExcluding": "7.1.6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.1", "versionEndExcluding": "7.2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/282d220bae5fbfc90cf0e3d5b5e42c00ad79f989"}, {"url": "https://git.kernel.org/stable/c/35551efb155e3b83445a6c3f66cb498d5efc182c"}], "title": "smp: Make CSD lock acquisition atomic for debug mode", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["kernel/smp.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "282d220bae5fbfc90cf0e3d5b5e42c00ad79f989", "status": "affected", "version": "b0473dcd4b1d7e2e44947e7ac1820c73a268821a", "versionType": "git"}, {"lessThan": "35551efb155e3b83445a6c3f66cb498d5efc182c", "status": "affected", "version": "b0473dcd4b1d7e2e44947e7ac1820c73a268821a", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["kernel/smp.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "7.1"}, {"lessThan": "7.1", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.6", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.2", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmp: Make CSD lock acquisition atomic for debug mode\n\nCommit b0473dcd4b1d (\"smp: Improve smp_call_function_single()\nCSD-lock diagnostics\") changed smp_call_function_single() so that,\nwhen CSD lock debugging is enabled, async !wait calls use the\ndestination CPU csd_data. That improves diagnostics, but it also removes\nthe single-writer property that made the old csd_lock() safe: multiple\nCPUs can now prepare the same destination CPU CSD concurrently.\n\ncsd_lock() currently waits for CSD_FLAG_LOCK to clear and then sets the\nbit with a non-atomic read-modify-write. Two senders can both see an\nunlocked CSD, set the bit, overwrite the callback fields, and enqueue\nthe same llist node. Re-adding a node that is already the queue head can\nmake node->next point to itself, leaving the target CPU stuck walking\ncall_single_queue. Later synchronous work, such as a TLB shootdown, can\nthen remain queued and trigger soft-lockup warnings or panics.\n\nKeep the single csd_lock() implementation, but when CSD lock debugging is\nenabled, acquire CSD_FLAG_LOCK with try_cmpxchg_acquire(). This makes the\ndestination CPU CSD a real atomic lock in the only configuration where it\ncan be shared by multiple remote senders, while preserving the existing\nnon-debug fast path."}], "id": "CVE-2026-68438", "lastModified": "2026-08-17T06:17:52.890", "metrics": {}, "published": "2026-08-12T00:17:44.013", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/282d220bae5fbfc90cf0e3d5b5e42c00ad79f989"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/35551efb155e3b83445a6c3f66cb498d5efc182c"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: smp: Make CSD lock acquisition atomic for debug mode", "id": "2514445", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2514445"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-821", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nsmp: Make CSD lock acquisition atomic for debug mode\nCommit b0473dcd4b1d (\"smp: Improve smp_call_function_single()\nCSD-lock diagnostics\") changed smp_call_function_single() so that,\nwhen CSD lock debugging is enabled, async !wait calls use the\ndestination CPU csd_data. That improves diagnostics, but it also removes\nthe single-writer property that made the old csd_lock() safe: multiple\nCPUs can now prepare the same destination CPU CSD concurrently.\ncsd_lock() currently waits for CSD_FLAG_LOCK to clear and then sets the\nbit with a non-atomic read-modify-write. Two senders can both see an\nunlocked CSD, set the bit, overwrite the callback fields, and enqueue\nthe same llist node. Re-adding a node that is already the queue head can\nmake node->next point to itself, leaving the target CPU stuck walking\ncall_single_queue. Later synchronous work, such as a TLB shootdown, can\nthen remain queued and trigger soft-lockup warnings or panics.\nKeep the single csd_lock() implementation, but when CSD lock debugging is\nenabled, acquire CSD_FLAG_LOCK with try_cmpxchg_acquire(). This makes the\ndestination CPU CSD a real atomic lock in the only configuration where it\ncan be shared by multiple remote senders, while preserving the existing\nnon-debug fast path.", "A flaw was found in the Linux kernel. When CSD (Call Single Data) lock debugging is enabled, the csd_lock() function's acquisition of the CSD lock is not atomic. This allows multiple central processing units (CPUs) to concurrently access and modify the same CSD data. A local attacker could exploit this race condition, causing the target CPU to become stuck in a loop while processing the call_single_queue. This can lead to soft-lockup warnings or system panics, effectively resulting in a Denial of Service (DoS)."], "name": "CVE-2026-68438", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:enterprise_linux_nvidia:", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux for NVIDIA 26"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Not affected", "package_name": "rhcos", "product_name": "Red Hat OpenShift Container Platform 4"}], "public_date": "2026-08-12T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-68438\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-68438\nhttps://lore.kernel.org/linux-cve-announce/2026081255-CVE-2026-68438-0cb0@gregkh/T"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[b0473dcd4b1d7e2e44947e7ac1820c73a268821a,282d220bae5fbfc90cf0e3d5b5e42c00ad79f989)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[b0473dcd4b1d7e2e44947e7ac1820c73a268821a,35551efb155e3b83445a6c3f66cb498d5efc182c)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "7.1"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,7.1)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.1.6,7.1.*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.2-rc5,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-08-12T16:00:04.248649+00:00", "updated": "2026-08-13T14:00:04.466128+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}