{"api_version":"1","generated_at":"2026-05-12T13:03:29+00:00","cve":"CVE-2026-43331","urls":{"html":"https://cve.report/CVE-2026-43331","api":"https://cve.report/api/cve/CVE-2026-43331.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-43331","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-43331"},"summary":{"title":"x86/kexec: Disable KCOV instrumentation after load_segments()","description":"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. ]","state":"PUBLISHED","assigner":"Linux","published_at":"2026-05-08 14:16:42","updated_at":"2026-05-08 14:16:42"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/de05c66fab8847237a9ca216934e56d3ee837f08","name":"https://git.kernel.org/stable/c/de05c66fab8847237a9ca216934e56d3ee837f08","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/917e3ad3321e75ca0223d5ccf26ceda116aa51e1","name":"https://git.kernel.org/stable/c/917e3ad3321e75ca0223d5ccf26ceda116aa51e1","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/1e3e98596c2769721ade0418434852fb3af4849a","name":"https://git.kernel.org/stable/c/1e3e98596c2769721ade0418434852fb3af4849a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-43331","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-43331","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 0d345996e4cb573f8cc81d49b3ee9a7fd2035bef 1e3e98596c2769721ade0418434852fb3af4849a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 0d345996e4cb573f8cc81d49b3ee9a7fd2035bef de05c66fab8847237a9ca216934e56d3ee837f08 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 0d345996e4cb573f8cc81d49b3ee9a7fd2035bef 917e3ad3321e75ca0223d5ccf26ceda116aa51e1 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.6","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.22 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.19.12 6.19.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"43331","cve":"CVE-2026-43331","epss":"0.000170000","percentile":"0.041290000","score_date":"2026-05-11","updated_at":"2026-05-12 00:01:18"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["arch/x86/kernel/Makefile","arch/x86/mm/Makefile"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"1e3e98596c2769721ade0418434852fb3af4849a","status":"affected","version":"0d345996e4cb573f8cc81d49b3ee9a7fd2035bef","versionType":"git"},{"lessThan":"de05c66fab8847237a9ca216934e56d3ee837f08","status":"affected","version":"0d345996e4cb573f8cc81d49b3ee9a7fd2035bef","versionType":"git"},{"lessThan":"917e3ad3321e75ca0223d5ccf26ceda116aa51e1","status":"affected","version":"0d345996e4cb573f8cc81d49b3ee9a7fd2035bef","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["arch/x86/kernel/Makefile","arch/x86/mm/Makefile"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.6"},{"lessThan":"6.6","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.22","versionType":"semver"},{"lessThanOrEqual":"6.19.*","status":"unaffected","version":"6.19.12","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.0","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.22","versionStartIncluding":"6.6","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.19.12","versionStartIncluding":"6.6","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.0","versionStartIncluding":"6.6","vulnerable":true}],"negate":false,"operator":"OR"}]}],"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. ]"}],"providerMetadata":{"dateUpdated":"2026-05-08T13:31:18.787Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"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"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-43331","datePublished":"2026-05-08T13:31:18.787Z","dateReserved":"2026-05-01T14:12:56.002Z","dateUpdated":"2026-05-08T13:31:18.787Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-05-08 14:16:42","lastModifiedDate":"2026-05-08 14:16:42","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"43331","Ordinal":"1","Title":"x86/kexec: Disable KCOV instrumentation after load_segments()","CVE":"CVE-2026-43331","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"43331","Ordinal":"1","NoteData":"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. ]","Type":"Description","Title":"x86/kexec: Disable KCOV instrumentation after load_segments()"}]}}}