CVE-2026-43418

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-43418", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-05-01T14:12:56.008Z", "datePublished": "2026-05-08T14:21:54.362Z", "dateUpdated": "2026-05-11T22:24:12.301Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-05-11T22:24:12.301Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched/mmcid: Prevent CID stalls due to concurrent forks\n\nA newly forked task is accounted as MMCID user before the task is visible\nin the process' thread list and the global task list. This creates the\nfollowing problem:\n\n CPU1\t\t\tCPU2\n fork()\n sched_mm_cid_fork(tnew1)\n tnew1->mm.mm_cid_users++;\n tnew1->mm_cid.cid = getcid()\n-> preemption\n\t\t\tfork()\n\t\t\t sched_mm_cid_fork(tnew2)\n\t\t\t tnew2->mm.mm_cid_users++;\n // Reaches the per CPU threshold\n\t\t\t mm_cid_fixup_tasks_to_cpus()\n\t\t\t for_each_other(current, p)\n\t\t\t ....\n\nAs tnew1 is not visible yet, this fails to fix up the already allocated CID\nof tnew1. As a consequence a subsequent schedule in might fail to acquire a\n(transitional) CID and the machine stalls.\n\nMove the invocation of sched_mm_cid_fork() after the new task becomes\nvisible in the thread and the task list to prevent this.\n\nThis also makes it symmetrical vs. exit() where the task is removed as CID\nuser before the task is removed from the thread and task lists."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["include/linux/sched.h", "kernel/fork.c", "kernel/sched/core.c"], "versions": [{"version": "fbd0e71dc370af73f6b316e4de9eed273dd90340", "lessThan": "f0189d49282e0458f3a737bd486c1ec048148f66", "status": "affected", "versionType": "git"}, {"version": "fbd0e71dc370af73f6b316e4de9eed273dd90340", "lessThan": "b2e48c429ec54715d16fefa719dd2fbded2e65be", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["include/linux/sched.h", "kernel/fork.c", "kernel/sched/core.c"], "versions": [{"version": "6.19", "status": "affected"}, {"version": "0", "lessThan": "6.19", "status": "unaffected", "versionType": "semver"}, {"version": "6.19.9", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.0", "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": "6.19", "versionEndExcluding": "6.19.9"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "7.0"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/f0189d49282e0458f3a737bd486c1ec048148f66"}, {"url": "https://git.kernel.org/stable/c/b2e48c429ec54715d16fefa719dd2fbded2e65be"}], "title": "sched/mmcid: Prevent CID stalls due to concurrent forks", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["include/linux/sched.h", "kernel/fork.c", "kernel/sched/core.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "f0189d49282e0458f3a737bd486c1ec048148f66", "status": "affected", "version": "fbd0e71dc370af73f6b316e4de9eed273dd90340", "versionType": "git"}, {"lessThan": "b2e48c429ec54715d16fefa719dd2fbded2e65be", "status": "affected", "version": "fbd0e71dc370af73f6b316e4de9eed273dd90340", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["include/linux/sched.h", "kernel/fork.c", "kernel/sched/core.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "6.19"}, {"lessThan": "6.19", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.19.*", "status": "unaffected", "version": "6.19.9", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.0", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "E825E7C3-FEAC-4FD3-8A81-78D7387948C9", "versionEndExcluding": "6.19.9", "versionStartIncluding": "6.19", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched/mmcid: Prevent CID stalls due to concurrent forks\n\nA newly forked task is accounted as MMCID user before the task is visible\nin the process' thread list and the global task list. This creates the\nfollowing problem:\n\n CPU1\t\t\tCPU2\n fork()\n sched_mm_cid_fork(tnew1)\n tnew1->mm.mm_cid_users++;\n tnew1->mm_cid.cid = getcid()\n-> preemption\n\t\t\tfork()\n\t\t\t sched_mm_cid_fork(tnew2)\n\t\t\t tnew2->mm.mm_cid_users++;\n // Reaches the per CPU threshold\n\t\t\t mm_cid_fixup_tasks_to_cpus()\n\t\t\t for_each_other(current, p)\n\t\t\t ....\n\nAs tnew1 is not visible yet, this fails to fix up the already allocated CID\nof tnew1. As a consequence a subsequent schedule in might fail to acquire a\n(transitional) CID and the machine stalls.\n\nMove the invocation of sched_mm_cid_fork() after the new task becomes\nvisible in the thread and the task list to prevent this.\n\nThis also makes it symmetrical vs. exit() where the task is removed as CID\nuser before the task is removed from the thread and task lists."}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nsched/mmcid: Prevenir bloqueos de CID debido a bifurcaciones concurrentes\n\nUna tarea reci\u00e9n bifurcada se contabiliza como usuario de MMCID antes de que la tarea sea visible en la lista de hilos del proceso y en la lista global de tareas. Esto crea el siguiente problema:\n\n CPU1\t\t\tCPU2\n fork()\n sched_mm_cid_fork(tnew1)\n tnew1 -> mm.mm_cid_users++;\n tnew1 -> mm_cid.cid = getcid()\n -> preemption\n\t\t\tfork()\n\t\t\t sched_mm_cid_fork(tnew2)\n\t\t\t tnew2 -> mm.mm_cid_users++;\n // Reaches the per CPU threshold\n\t\t\t mm_cid_fixup_tasks_to_cpus()\n\t\t\t for_each_other(current, p)\n\t\t\t ....\n\nComo tnew1 a\u00fan no es visible, esto no logra corregir el CID ya asignado de tnew1. Como consecuencia, una planificaci\u00f3n posterior podr\u00eda no lograr adquirir un CID (transitorio) y la m\u00e1quina se bloquea.\n\nMover la invocaci\u00f3n de sched_mm_cid_fork() despu\u00e9s de que la nueva tarea se vuelva visible en la lista de hilos y en la lista de tareas para prevenir esto.\n\nEsto tambi\u00e9n lo hace sim\u00e9trico frente a exit() donde la tarea se elimina como usuario de CID antes de que la tarea sea eliminada de las listas de hilos y tareas."}], "id": "CVE-2026-43418", "lastModified": "2026-11-11T20:10:00.273", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 5.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}]}, "published": "2026-05-08T15:16:53.803", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/b2e48c429ec54715d16fefa719dd2fbded2e65be"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/f0189d49282e0458f3a737bd486c1ec048148f66"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "NVD-CWE-noinfo"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: sched/mmcid: Prevent CID stalls due to concurrent forks", "id": "2468211", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2468211"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.0", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-821", "details": ["A flaw was found in the Linux kernel's `sched/mmcid` component. When new tasks are created concurrently, a race condition can occur where a task is accounted as a Memory Management Context ID (MMCID) user before it is fully registered in the system's task lists. This can lead to an incorrect allocation of Context IDentifiers (CIDs). As a result, the system may fail to acquire a necessary CID, causing the machine to stall and resulting in a Denial of Service (DoS)."], "name": "CVE-2026-43418", "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": "Out of support scope", "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"}], "public_date": "2026-05-08T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-43418\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-43418\nhttps://lore.kernel.org/linux-cve-announce/2026050846-CVE-2026-43418-8b7a@gregkh/T"], "threat_severity": "Moderate"}

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