{"attribution":"This product uses data from the NVD API but is not endorsed or certified by the NVD.","cve":{"id":"CVE-2026-98134","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","published":"2026-09-25T11:17:44.820","lastModified":"2026-10-21T13:21:24.020","vulnStatus":"Modified","cveTags":[],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: check_cond_jmp_op(): properly infer if register is null\n\nNicholas Carlini reported a bug when verifier can incorrectly infer\nthat a pointer is non-null. The bug occurs when two pointers are\ncompared and one of them has a type w/o PTR_MAYBE_NULL flag,\nbut which allows a value to be NULL at runtime.\nHere is an example:\n\n  // `a` is PTR_TO_MEM | MEM_RDONLY | PTR_UNTRUSTED\n  // `a` is 0 at runtime.\n  // `b` is PTR_TO_MAP_VALUE | PTR_MAYBE_NULL\n  void *a = bpf_rdonly_cast(0, 0);\n  int  *b = bpf_map_lookup_elem(...);\n\n  if (a == b)\n    *b = 42;  // verifier does not catch null pointer dereference\n\nThis happens because of a special case in check_cond_jmp_op(),\nwhich attempts to strip PTR_MAYBE_NULL flags from pointer types,\nwhen processing comparisons like `rA == rB`, if either rA or rB can't\nbe null.\n\nThe non-null property is derived based on the absence of\nPTR_MAYBE_NULL flag on rA's or rB's type. But that is not sufficient\nfor types like PTR_TO_MEM, as in the example.\n\nThis patch replaces type_may_be_null() call with reg_not_null(),\nwhich contains an allowlist of types for which absence of\nPTR_MAYBE_NULL actually means that the value can't be NULL at runtime.\n\nAt the moment, the list in the reg_not_null() omits two types for\nwhich PTR_MAYBE_NULL is applicable: PTR_TO_XDP_SOCK and PTR_TO_BUF.\nIn order to remain backward compatible, and assuming that only\ncomparison between pointers of the same type makes sense,\nthis commit extends reg_not_null(). W/o such an extension e.g.\nverifier_jeq_infer_not_null/null_ptr_to_map_value fails.\n\nreg_not_null() can be extended further, but I deem that out of scope\nfor the fix at hand. Explicit base_type(...) != PTR_TO_BTF_ID\nchecks in the check_cond_jmp_op() can be removed with migration to\nreg_not_null(), but that is a behavioural change, as the special case\nwould start matching for PTR_TO_BTF_ID that is also is_trusted_reg().\nI omit the behavioural change from this commit."}],"affected":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","affectedData":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","programFiles":["kernel/bpf/verifier.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","versions":[{"version":"befae75856ab406a3f3fab2aa2118cf3b2dfe3e6","lessThan":"d51cd486930f5bcfd4b55d55ab8e47b03f93d2ed","versionType":"git","status":"affected"},{"version":"befae75856ab406a3f3fab2aa2118cf3b2dfe3e6","lessThan":"dfd8f8adda565e08c370c45cf9d6b2511ba9b5c6","versionType":"git","status":"affected"},{"version":"befae75856ab406a3f3fab2aa2118cf3b2dfe3e6","lessThan":"9bf96b4347f541604b3caadeabda0773d9ceaf2a","versionType":"git","status":"affected"},{"version":"befae75856ab406a3f3fab2aa2118cf3b2dfe3e6","lessThan":"b55c9f019e169ed0d01394f96e172286a8b21b99","versionType":"git","status":"affected"},{"version":"befae75856ab406a3f3fab2aa2118cf3b2dfe3e6","lessThan":"d3ef6c097ba078e1f8c7239d76a0ce8b61e75095","versionType":"git","status":"affected"}]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","programFiles":["kernel/bpf/verifier.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","versions":[{"version":"6.2","status":"affected"},{"version":"0","lessThan":"6.2","versionType":"semver","status":"unaffected"},{"version":"6.6.160","lessThanOrEqual":"6.6.*","versionType":"semver","status":"unaffected"},{"version":"6.12.114","lessThanOrEqual":"6.12.*","versionType":"semver","status":"unaffected"},{"version":"6.18.57","lessThanOrEqual":"6.18.*","versionType":"semver","status":"unaffected"},{"version":"7.2.7","lessThanOrEqual":"7.2.*","versionType":"semver","status":"unaffected"},{"version":"7.3","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":"CWE-476"}]}],"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"7.2.7","matchCriteriaId":"DBB72E3F-F916-4169-9DD1-11732F9A549E"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:7.3:rc1:*:*:*:*:*:*","matchCriteriaId":"11E35E1B-5DB4-4AB9-9706-CD73B799EADF"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/9bf96b4347f541604b3caadeabda0773d9ceaf2a","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/b55c9f019e169ed0d01394f96e172286a8b21b99","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/d3ef6c097ba078e1f8c7239d76a0ce8b61e75095","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/d51cd486930f5bcfd4b55d55ab8e47b03f93d2ed","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/dfd8f8adda565e08c370c45cf9d6b2511ba9b5c6","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}]}}