GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

CVE-2026-43331 (GCVE-0-2026-43331)

Vulnerability from cvelistv5 – Published: 2026-05-08 13:31 – Updated: 2026-06-19 11:58
VLAI
Title
x86/kexec: Disable KCOV instrumentation after load_segments()
Summary
In the Linux kernel, the following vulnerability has been resolved: x86/kexec: Disable KCOV instrumentation after load_segments() The load_segments() function changes segment registers, invalidating GS base (which KCOV relies on for per-cpu data). When CONFIG_KCOV is enabled, any subsequent instrumented C code call (e.g. native_gdt_invalidate()) begins crashing the kernel in an endless loop. To reproduce the problem, it's sufficient to do kexec on a KCOV-instrumented kernel: $ kexec -l /boot/otherKernel $ kexec -e The real-world context for this problem is enabling crash dump collection in syzkaller. For this, the tool loads a panic kernel before fuzzing and then calls makedumpfile after the panic. This workflow requires both CONFIG_KEXEC and CONFIG_KCOV to be enabled simultaneously. Adding safeguards directly to the KCOV fast-path (__sanitizer_cov_trace_pc()) is also undesirable as it would introduce an extra performance overhead. Disabling instrumentation for the individual functions would be too fragile, so disable KCOV instrumentation for the entire machine_kexec_64.c and physaddr.c. If coverage-guided fuzzing ever needs these components in the future, other approaches should be considered. The problem is not relevant for 32 bit kernels as CONFIG_KCOV is not supported there. [ bp: Space out comment for better readability. ]
Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 0d345996e4cb573f8cc81d49b3ee9a7fd2035bef , < 0e96cd314c0d819c1635d68125a4d77852c2162e (git)
Affected: 0d345996e4cb573f8cc81d49b3ee9a7fd2035bef , < 593d67032544b9271094fc9b43e437e017cb2b2f (git)
Affected: 0d345996e4cb573f8cc81d49b3ee9a7fd2035bef , < 1e3e98596c2769721ade0418434852fb3af4849a (git)
Affected: 0d345996e4cb573f8cc81d49b3ee9a7fd2035bef , < de05c66fab8847237a9ca216934e56d3ee837f08 (git)
Affected: 0d345996e4cb573f8cc81d49b3ee9a7fd2035bef , < 917e3ad3321e75ca0223d5ccf26ceda116aa51e1 (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.6
Unaffected: 0 , < 6.6 (semver)
Unaffected: 6.6.143 , ≤ 6.6.* (semver)
Unaffected: 6.12.93 , ≤ 6.12.* (semver)
Unaffected: 6.18.22 , ≤ 6.18.* (semver)
Unaffected: 6.19.12 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "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": "0e96cd314c0d819c1635d68125a4d77852c2162e",
              "status": "affected",
              "version": "0d345996e4cb573f8cc81d49b3ee9a7fd2035bef",
              "versionType": "git"
            },
            {
              "lessThan": "593d67032544b9271094fc9b43e437e017cb2b2f",
              "status": "affected",
              "version": "0d345996e4cb573f8cc81d49b3ee9a7fd2035bef",
              "versionType": "git"
            },
            {
              "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": "6.6.*",
              "status": "unaffected",
              "version": "6.6.143",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.93",
              "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": "6.6.143",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.93",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                },
                {
                  "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\u0027s 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": "2026-06-19T11:58:29.321Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "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"
      }
    }
  },
  "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": "2026-06-19T11:58:29.321Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-43331",
      "date": "2026-09-14",
      "epss": "0.00122",
      "percentile": "0.02245"
    },
    "microsoft_vex": {
      "current_release_date": "2026-07-02T14:43:42.000Z",
      "cve": "CVE-2026-43331",
      "id": "msrc_CVE-2026-43331",
      "initial_release_date": "2026-05-02T00:00:00.000Z",
      "product_status:fixed": "1",
      "product_status:known_affected": "1",
      "product_status:under_investigation": "4",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "x86/kexec: Disable KCOV instrumentation after load_segments()",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-43331.json",
      "version": "7"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-43331\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-05-08T14:16:42.763\",\"lastModified\":\"2026-06-19T13:16:29.693\",\"vulnStatus\":\"Modified\",\"cveTags\":[],\"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\u0027s 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\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"arch/x86/kernel/Makefile\",\"arch/x86/mm/Makefile\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"0d345996e4cb573f8cc81d49b3ee9a7fd2035bef\",\"lessThan\":\"0e96cd314c0d819c1635d68125a4d77852c2162e\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"0d345996e4cb573f8cc81d49b3ee9a7fd2035bef\",\"lessThan\":\"593d67032544b9271094fc9b43e437e017cb2b2f\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"0d345996e4cb573f8cc81d49b3ee9a7fd2035bef\",\"lessThan\":\"1e3e98596c2769721ade0418434852fb3af4849a\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"0d345996e4cb573f8cc81d49b3ee9a7fd2035bef\",\"lessThan\":\"de05c66fab8847237a9ca216934e56d3ee837f08\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"0d345996e4cb573f8cc81d49b3ee9a7fd2035bef\",\"lessThan\":\"917e3ad3321e75ca0223d5ccf26ceda116aa51e1\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"arch/x86/kernel/Makefile\",\"arch/x86/mm/Makefile\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.6\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.6\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.143\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.93\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.22\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.19.12\",\"lessThanOrEqual\":\"6.19.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.0\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":5.5,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"NVD-CWE-noinfo\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.6\",\"versionEndExcluding\":\"6.18.22\",\"matchCriteriaId\":\"CB33D19D-30CB-4E4C-9018-2230BD327607\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.19\",\"versionEndExcluding\":\"6.19.12\",\"matchCriteriaId\":\"0A2B9540-02D5-41B4-B16A-82AF66FD4F36\"},{\"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,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*\",\"matchCriteriaId\":\"02259FDA-961B-47BC-AE7F-93D7EC6E90C2\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*\",\"matchCriteriaId\":\"58A9FEFF-C040-420D-8F0A-BFDAAA1DF258\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*\",\"matchCriteriaId\":\"1D2315C0-D46F-4F85-9754-F9E5E11374A6\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/0e96cd314c0d819c1635d68125a4d77852c2162e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/1e3e98596c2769721ade0418434852fb3af4849a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/593d67032544b9271094fc9b43e437e017cb2b2f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/917e3ad3321e75ca0223d5ccf26ceda116aa51e1\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/de05c66fab8847237a9ca216934e56d3ee837f08\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}",
    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-06-28T07:36:55+00:00",
      "cve": "CVE-2026-43331",
      "id": "CVE-2026-43331",
      "initial_release_date": "2026-05-08T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: x86/kexec: Disable KCOV instrumentation after load_segments()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43331.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-06-20T02:30:22Z",
      "cve": "CVE-2026-43331",
      "id": "CVE-2026-43331",
      "initial_release_date": "2026-05-13T03:35:16Z",
      "product_status:known_affected": "15",
      "product_status:known_not_affected": "276",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-43331",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-43331.json",
      "version": "4"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.