{"id":"CVE-2026-72111","summary":"bpf: Reset register bounds before narrowing retval range in check_mem_access()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reset register bounds before narrowing retval range in check_mem_access()\n\nWhen the BPF verifier processes a context load of an LSM hook return\nvalue, it calls __mark_reg_s32_range() to narrow the register to the\nhook's valid range. However, __mark_reg_s32_range() intersects the new\nrange with the register's existing bounds using max_t()/min_t() rather\nthan replacing them.\n\nIf the destination register carries stale bounds from a prior instruction\n(e.g. BPF_MOV64_IMM), the intersection can produce a range narrower than\nreality. The verifier then believes it knows the register's exact value,\nwhile at runtime the actual hook return value is loaded, creating a\nverifier/runtime mismatch that can be used to bypass BPF memory safety\nchecks.\n\nThe else branch already calls mark_reg_unknown() to reset register state\nbefore any narrowing. Apply the same reset in the is_retval path so\nstale bounds are cleared before __mark_reg_s32_range() intersects.","modified":"2026-10-24T02:30:43.795073120Z","published":"2026-08-15T05:52:52.538Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72111.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0993dc5fc619c0b25ab1310cb11d65e78351c0fe"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5a55f9aecc08990940e70f0c7048a80850c5a16a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5e0b273e0a62cc04ec338c7b502797c66c2ed42a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bde92f65042ec14389782dd223f706bf6b59ce5d"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72111.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72111"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"5d99e198be279045e6ecefe220f5c52f8ce9bfd5"},{"fixed":"bde92f65042ec14389782dd223f706bf6b59ce5d"},{"fixed":"0993dc5fc619c0b25ab1310cb11d65e78351c0fe"},{"fixed":"5a55f9aecc08990940e70f0c7048a80850c5a16a"},{"fixed":"5e0b273e0a62cc04ec338c7b502797c66c2ed42a"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.10.13"},{"fixed":"6.11"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.11.2"},{"fixed":"6.12"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"1050727d83e70449991c29dd1cf29fe936a63da3"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"27ca3e20fe80be85a92b10064dfeb56cb2564b1c"}]}],"versions":["v6.10.14","v6.10.13","v6.11.11","v6.11.10","v6.11.9","v6.11.8","v6.11.7","v6.11.6","v6.11.5","v6.11.4","v6.11.3","v6.11.2"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72111.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.12.0"},{"fixed":"6.12.103"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.40"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72111.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"}]}