{"id":"CVE-2026-92499","revision":"42bc30b844014bad90a792e854bbf1cf","records":[{"revision":"42bc30b844014bad90a792e854bbf1cf","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-92499","aliases":[],"title":"ext4: validate readdir offset before accessing dirent","description":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: validate readdir offset before accessing dirent\n\nA corrupted directory can trigger the following KASAN report when\next4_readdir() resumes from an invalid position:\n\n  BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x5ef/0x820\n  Read of size 2 at addr ffff88810a646000 by task repro_linear/509\n\n  Call Trace:\n   <TASK>\n   dump_stack_lvl+0x53/0x70\n   print_report+0xd0/0x630\n   kasan_report+0xce/0x100\n   __ext4_check_dir_entry+0x5ef/0x820\n   ext4_readdir+0xcde/0x2b70\n   iterate_dir+0x1a1/0x520\n   __x64_sys_getdents64+0x12b/0x220\n   do_syscall_64+0xf9/0x540\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n   </TASK>\n\nKASAN reports use-after-free because the out-of-bounds access lands in an\nadjacent freed page. The directory buffer itself is still referenced.\n\next4_dir_llseek() invalidates the directory cookie so that ext4_readdir()\nrescans directory entries from the start of the block. The rescan checks\nonly the lower bound of rec_len before advancing. A corrupted rec_len can\ntherefore place the offset where the block has insufficient space for a\ncomplete directory entry. The rescan itself may dereference that truncated\nentry, or the main loop may pass it to __ext4_check_dir_entry(). The latter\nreads de->rec_len before validating the range. For example:\n\n  block offset  0                           4092  4096\n                |---- de1.rec_len = 4092 -----|----|\n                                               de2.inode\n                                                    | de2.rec_len\n                                                    ^ OOB, reported as UAF\n\nde2 starts at offset 4092 in this 4 KiB block. Its four-byte inode fits in\nthe block, but its rec_len starts at offset 4096 and crosses the boundary.\n\nThe minimum safe length is inode-dependent. Encrypted and casefolded\ndirectory entries need eight additional hash bytes, while a valid metadata\nchecksum tail is only 12 bytes.\n\nCache the metadata checksum feature state and derive the minimum directory\nentry length from the on-disk format. Use it to bound both the rescan and\nthe offset passed to the main loop. Report an offset in a truncated block\ntail and skip the remainder of the block, while continuing to accept an\noffset exactly at the block boundary.","state":0,"publishedAt":"2026-09-17T16:10:13.391+00:00","modifiedAt":"2026-10-19T09:04:05.335+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/dir.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"ac27a0ec112a089f1a5102bc8dffc79c8c815571\",\n                            \"lessThan\": \"64d445d40e5ea4c4d4d88880db753b370cb69161\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"ac27a0ec112a089f1a5102bc8dffc79c8c815571\",\n                            \"lessThan\": \"b4c728577933753180e3e97f08424d5bcaff705e\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"ac27a0ec112a089f1a5102bc8dffc79c8c815571\",\n                            \"lessThan\": \"bc4b7b0414c33b2c8898eb04386df0d21a13dad8\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"fs/ext4/dir.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"2.6.19\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"2.6.19\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.52\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.6\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/64d445d40e5ea4c4d4d88880db753b370cb69161","https://git.kernel.org/stable/c/b4c728577933753180e3e97f08424d5bcaff705e","https://git.kernel.org/stable/c/bc4b7b0414c33b2c8898eb04386df0d21a13dad8"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-92499","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-92499","identifiers":["CVE-2026-92499"]},"retained":false,"historicalAffected":[]}],"coverage":[]}