{"id":"CVE-2026-43067","revision":"b8d79523efa54d45b434e6a1d2179a01","records":[{"revision":"b8d79523efa54d45b434e6a1d2179a01","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-43067","aliases":[],"title":"ext4: handle wraparound when searching for blocks for indirect mapped blocks","description":"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->ac_g_ex.fe_group is >= ngroups (for instance, if the goal\n   group was populated via stream allocation from s_mb_last_groups),\n   then start will be >= 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().","state":0,"publishedAt":"2026-05-05T15:23:26.717+00:00","modifiedAt":"2026-10-19T19:06:12.38+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"fs/ext4/mballoc.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"9d89b9d55e25cb340c5b4b769876edc551b7a9ff\",\n                            \"lessThan\": \"f89bba144938921a2249237ad04a0183ff3f8930\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1b0edd6022a3f44ce87fea9959a9310f4628fbea\",\n                            \"lessThan\": \"83170a05908b6cf2fb3235d3065bf613ff866f3c\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9eea2f57d11b30049ff996ac3eff6e0dc8089e5f\",\n                            \"lessThan\": \"4bec4a498ce86314d470ae6144120461f2138c29\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"34c803edc0b3365a42efcf9815acab63b4cf54e0\",\n                            \"lessThan\": \"12624c5b724a81e14e532972b40d863b0de3b7d1\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"321ed8d559c951e71ad2d2d69a4cf0445644e865\",\n                            \"lessThan\": \"2a368ccddfc492a0aa951e2caef2985f20e96503\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"4865c768b563deff1b6a6384e74a62f143427b42\",\n                            \"lessThan\": \"bb81702370fad22c06ca12b6e1648754dbc37e0f\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"16fce6b6c0b247258c6c217fce5a48abf50f6964\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"5.15.203\",\n                            \"lessThan\": \"5.16\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"fs/ext4/mballoc.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"6.1.167\",\n                            \"lessThan\": \"6.1.168\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.130\",\n                            \"lessThan\": \"6.6.134\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.77\",\n                            \"lessThan\": \"6.12.80\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.14\",\n                            \"lessThan\": \"6.18.21\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.19.4\",\n                            \"lessThan\": \"6.19.11\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8,"severity":"CRITICAL"}],"references":["https://git.kernel.org/stable/c/f89bba144938921a2249237ad04a0183ff3f8930","https://git.kernel.org/stable/c/83170a05908b6cf2fb3235d3065bf613ff866f3c","https://git.kernel.org/stable/c/4bec4a498ce86314d470ae6144120461f2138c29","https://git.kernel.org/stable/c/12624c5b724a81e14e532972b40d863b0de3b7d1","https://git.kernel.org/stable/c/2a368ccddfc492a0aa951e2caef2985f20e96503","https://git.kernel.org/stable/c/bb81702370fad22c06ca12b6e1648754dbc37e0f"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-43067","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-43067","identifiers":["CVE-2026-43067"]},"retained":false,"historicalAffected":[]}],"coverage":[]}