CVE-2026-43331

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-43331", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-05-01T14:12:56.002Z", "datePublished": "2026-05-08T13:31:18.787Z", "dateUpdated": "2026-06-19T11:58:29.321Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-06-19T11:58:29.321Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/kexec: Disable KCOV instrumentation after load_segments()\n\nThe load_segments() function changes segment registers, invalidating GS base\n(which KCOV relies on for per-cpu data). When CONFIG_KCOV is enabled, any\nsubsequent instrumented C code call (e.g. native_gdt_invalidate()) begins\ncrashing the kernel in an endless loop.\n\nTo reproduce the problem, it's sufficient to do kexec on a KCOV-instrumented\nkernel:\n\n $ kexec -l /boot/otherKernel\n $ kexec -e\n\nThe real-world context for this problem is enabling crash dump collection in\nsyzkaller. For this, the tool loads a panic kernel before fuzzing and then\ncalls makedumpfile after the panic. This workflow requires both CONFIG_KEXEC\nand CONFIG_KCOV to be enabled simultaneously.\n\nAdding safeguards directly to the KCOV fast-path (__sanitizer_cov_trace_pc())\nis also undesirable as it would introduce an extra performance overhead.\n\nDisabling instrumentation for the individual functions would be too fragile,\nso disable KCOV instrumentation for the entire machine_kexec_64.c and\nphysaddr.c. If coverage-guided fuzzing ever needs these components in the\nfuture, other approaches should be considered.\n\nThe problem is not relevant for 32 bit kernels as CONFIG_KCOV is not supported\nthere.\n\n [ bp: Space out comment for better readability. ]"}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["arch/x86/kernel/Makefile", "arch/x86/mm/Makefile"], "versions": [{"version": "0d345996e4cb573f8cc81d49b3ee9a7fd2035bef", "lessThan": "0e96cd314c0d819c1635d68125a4d77852c2162e", "status": "affected", "versionType": "git"}, {"version": "0d345996e4cb573f8cc81d49b3ee9a7fd2035bef", "lessThan": "593d67032544b9271094fc9b43e437e017cb2b2f", "status": "affected", "versionType": "git"}, {"version": "0d345996e4cb573f8cc81d49b3ee9a7fd2035bef", "lessThan": "1e3e98596c2769721ade0418434852fb3af4849a", "status": "affected", "versionType": "git"}, {"version": "0d345996e4cb573f8cc81d49b3ee9a7fd2035bef", "lessThan": "de05c66fab8847237a9ca216934e56d3ee837f08", "status": "affected", "versionType": "git"}, {"version": "0d345996e4cb573f8cc81d49b3ee9a7fd2035bef", "lessThan": "917e3ad3321e75ca0223d5ccf26ceda116aa51e1", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["arch/x86/kernel/Makefile", "arch/x86/mm/Makefile"], "versions": [{"version": "6.6", "status": "affected"}, {"version": "0", "lessThan": "6.6", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.143", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.93", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.22", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.19.12", "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": "6.6", "versionEndExcluding": "6.6.143"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6", "versionEndExcluding": "6.12.93"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6", "versionEndExcluding": "6.18.22"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6", "versionEndExcluding": "6.19.12"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6", "versionEndExcluding": "7.0"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/0e96cd314c0d819c1635d68125a4d77852c2162e"}, {"url": "https://git.kernel.org/stable/c/593d67032544b9271094fc9b43e437e017cb2b2f"}, {"url": "https://git.kernel.org/stable/c/1e3e98596c2769721ade0418434852fb3af4849a"}, {"url": "https://git.kernel.org/stable/c/de05c66fab8847237a9ca216934e56d3ee837f08"}, {"url": "https://git.kernel.org/stable/c/917e3ad3321e75ca0223d5ccf26ceda116aa51e1"}], "title": "x86/kexec: Disable KCOV instrumentation after load_segments()", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

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When CONFIG_KCOV is enabled, any\nsubsequent instrumented C code call (e.g. native_gdt_invalidate()) begins\ncrashing the kernel in an endless loop.\n\nTo reproduce the problem, it's sufficient to do kexec on a KCOV-instrumented\nkernel:\n\n $ kexec -l /boot/otherKernel\n $ kexec -e\n\nThe real-world context for this problem is enabling crash dump collection in\nsyzkaller. For this, the tool loads a panic kernel before fuzzing and then\ncalls makedumpfile after the panic. This workflow requires both CONFIG_KEXEC\nand CONFIG_KCOV to be enabled simultaneously.\n\nAdding safeguards directly to the KCOV fast-path (__sanitizer_cov_trace_pc())\nis also undesirable as it would introduce an extra performance overhead.\n\nDisabling instrumentation for the individual functions would be too fragile,\nso disable KCOV instrumentation for the entire machine_kexec_64.c and\nphysaddr.c. If coverage-guided fuzzing ever needs these components in the\nfuture, other approaches should be considered.\n\nThe problem is not relevant for 32 bit kernels as CONFIG_KCOV is not supported\nthere.\n\n [ bp: Space out comment for better readability. ]"}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nx86/kexec: Deshabilitar la instrumentaci\u00f3n KCOV despu\u00e9s de load_segments()\n\nLa funci\u00f3n load_segments() cambia los registros de segmento, invalidando la base GS (en la que KCOV se basa para los datos por CPU). Cuando CONFIG_KCOV est\u00e1 habilitado, cualquier llamada posterior a c\u00f3digo C instrumentado (por ejemplo, native_gdt_invalidate()) comienza a bloquear el kernel en un bucle infinito.\n\nPara reproducir el problema, es suficiente con hacer kexec en un kernel instrumentado con KCOV:\n\n $ kexec -l /boot/otherKernel\n $ kexec -e\n\nEl contexto real de este problema es la habilitaci\u00f3n de la recolecci\u00f3n de volcados de fallos en syzkaller. Para esto, la herramienta carga un kernel de p\u00e1nico antes del fuzzing y luego llama a makedumpfile despu\u00e9s del p\u00e1nico. Este flujo de trabajo requiere que tanto CONFIG_KEXEC como CONFIG_KCOV est\u00e9n habilitados simult\u00e1neamente.\n\nA\u00f1adir salvaguardas directamente a la ruta r\u00e1pida de KCOV (__sanitizer_cov_trace_pc()) tambi\u00e9n es indeseable ya que introducir\u00eda una sobrecarga de rendimiento adicional.\n\nDeshabilitar la instrumentaci\u00f3n para las funciones individuales ser\u00eda demasiado fr\u00e1gil, as\u00ed que se deshabilita la instrumentaci\u00f3n KCOV para todo machine_kexec_64.c y physaddr.c. Si el fuzzing guiado por cobertura alguna vez necesita estos componentes en el futuro, se deber\u00edan considerar otros enfoques.\n\nEl problema no es relevante para kernels de 32 bits ya que CONFIG_KCOV no es compatible all\u00ed.\n\n [ bp: Espaciar el comentario para una mejor legibilidad. ]"}], "id": "CVE-2026-43331", "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": "2026-05-08T14:16:42.763", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/0e96cd314c0d819c1635d68125a4d77852c2162e"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/1e3e98596c2769721ade0418434852fb3af4849a"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/593d67032544b9271094fc9b43e437e017cb2b2f"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/917e3ad3321e75ca0223d5ccf26ceda116aa51e1"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/de05c66fab8847237a9ca216934e56d3ee837f08"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "NVD-CWE-noinfo"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: x86/kexec: Disable KCOV instrumentation after load_segments()", "id": "2468042", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2468042"}, "csaw": false, "details": ["A flaw was found in the Linux kernel. When Kernel Coverage (KCOV) instrumentation is enabled, a local user performing a kexec operation can trigger an invalid state within the x86/kexec component. This invalid state, related to the GS base that KCOV relies on for per-CPU data, causes the kernel to crash in an endless loop. This vulnerability leads to a Denial of Service (DoS) for the affected system."], "name": "CVE-2026-43331", "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"}], "public_date": "2026-05-08T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-43331\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-43331\nhttps://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-43331.mbox"]}

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