{"id":"CVE-2026-43067","summary":"ext4: handle wraparound when searching for blocks for indirect mapped blocks","details":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: handle wraparound when searching for blocks for indirect mapped blocks\n\nCommit 4865c768b563 (\"ext4: always allocate blocks only from groups\ninode can use\") restricts what blocks will be allocated for indirect\nblock based files to block numbers that fit within 32-bit block\nnumbers.\n\nHowever, when using a review bot running on the latest Gemini LLM to\ncheck this commit when backporting into an LTS based kernel, it raised\nthis concern:\n\n   If ac-\u003eac_g_ex.fe_group is \u003e= ngroups (for instance, if the goal\n   group was populated via stream allocation from s_mb_last_groups),\n   then start will be \u003e= ngroups.\n\n   Does this allow allocating blocks beyond the 32-bit limit for\n   indirect block mapped files? The commit message mentions that\n   ext4_mb_scan_groups_linear() takes care to not select unsupported\n   groups. However, its loop uses group = *start, and the very first\n   iteration will call ext4_mb_scan_group() with this unsupported\n   group because next_linear_group() is only called at the end of the\n   iteration.\n\nAfter reviewing the code paths involved and considering the LLM\nreview, I determined that this can happen when there is a file system\nwhere some files/directories are extent-mapped and others are\nindirect-block mapped.  To address this, add a safety clamp in\next4_mb_scan_groups().","modified":"2026-10-20T10:31:05.616178177Z","published":"2026-05-05T15:23:26.717Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43067.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/12624c5b724a81e14e532972b40d863b0de3b7d1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2a368ccddfc492a0aa951e2caef2985f20e96503"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4bec4a498ce86314d470ae6144120461f2138c29"},{"type":"WEB","url":"https://git.kernel.org/stable/c/83170a05908b6cf2fb3235d3065bf613ff866f3c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bb81702370fad22c06ca12b6e1648754dbc37e0f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f89bba144938921a2249237ad04a0183ff3f8930"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43067.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-43067"},{"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":"9d89b9d55e25cb340c5b4b769876edc551b7a9ff"},{"fixed":"f89bba144938921a2249237ad04a0183ff3f8930"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"1b0edd6022a3f44ce87fea9959a9310f4628fbea"},{"fixed":"83170a05908b6cf2fb3235d3065bf613ff866f3c"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"9eea2f57d11b30049ff996ac3eff6e0dc8089e5f"},{"fixed":"4bec4a498ce86314d470ae6144120461f2138c29"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"34c803edc0b3365a42efcf9815acab63b4cf54e0"},{"fixed":"12624c5b724a81e14e532972b40d863b0de3b7d1"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"321ed8d559c951e71ad2d2d69a4cf0445644e865"},{"fixed":"2a368ccddfc492a0aa951e2caef2985f20e96503"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"4865c768b563deff1b6a6384e74a62f143427b42"},{"fixed":"bb81702370fad22c06ca12b6e1648754dbc37e0f"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"5.15.203"},{"fixed":"5.16"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"16fce6b6c0b247258c6c217fce5a48abf50f6964"}]}],"versions":["v6.1.167","v6.6.133","v6.6.132","v6.6.131","v6.6.130","v6.12.79","v6.12.78","v6.12.77","v6.18.20","v6.18.19","v6.18.18","v6.18.17","v6.18.16","v6.18.15","v6.18.14","v6.19.10","v6.19.9","v6.19.8","v6.19.7","v6.19.6","v6.19.5","v6.19.4","v5.15.223","v5.15.222","v5.15.221","v5.15.220","v5.15.219","v5.15.218","v5.15.217","v5.15.216","v5.15.215","v5.15.214","v5.15.213","v5.15.212","v5.15.211","v5.15.210","v5.15.209","v5.15.208","v5.15.207","v5.15.206","v5.15.205","v5.15.204","v5.15.203"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-43067.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.1.167"},{"fixed":"6.1.168"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.6.130"},{"fixed":"6.6.134"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.12.77"},{"fixed":"6.12.80"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.18.14"},{"fixed":"6.18.21"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.4"},{"fixed":"6.19.11"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-43067.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}