{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89786", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.766Z", "datePublished": "2026-09-16T08:48:23.730Z", "dateUpdated": "2026-10-19T08:52:39.655Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:52:39.655Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: fix out-of-bounds read in ext4_read_inline_dir()\n\next4_read_inline_dir() can read a dirent header past the end of its inline\nbuffer, triggering a slab-out-of-bounds read during getdents64():\n\n BUG: KASAN: slab-out-of-bounds in __ext4_check_dir_entry\n Read of size 2 at addr ffff88800f3dd23c by task exploit/148\n ...\n __ext4_check_dir_entry\n ext4_read_inline_dir\n iterate_dir\n\nThe dirent payload lives in a buffer of exactly inline_size bytes:\n\n\tdir_buf = kmalloc(inline_size, GFP_NOFS);\n\nbut iteration runs in a position space extra_offset bytes larger\n(extra_size = extra_offset + inline_size) so the synthetic \".\" and \"..\"\nland at their block-dir offsets. A dirent is formed at \"dir_buf + pos -\nextra_offset\", yet the ext4_check_dir_entry() length argument uses the\nlarger extra_size. A position whose dirent header would extend past\nextra_size is therefore accepted, and the rescan loop's rec_len probe and\next4_check_dir_entry() dereference de->rec_len before the entry is rejected.\n\nReject a position whose minimum-size dirent header would not fit within\nextra_size before forming de, in both the rescan and main loops, and pass\ninline_size rather than extra_size to ext4_check_dir_entry() so the length\ncheck matches the physical buffer." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H", "baseScore": 9.1, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - The slab OOB is in ext4_read_inline_dir(), reached from getdents64 via iterate_dir→ext4_readdir. nfsd_readdir does vfs_llseek plus iterate_dir, and ksmbd QUERY_DIRECTORY also calls iterate_dir, so a remote NFS/SMB client can trigger the same path on an ext4-backed export.\nAC:L - A crafted inline directory with attacker-controlled rec_len values (or a seek/NFS cookie that lands ctx->pos near extra_size) deterministically forms a dirent past kmalloc(inline_size) and dereferences de->rec_len. No race or attacker-uncontrollable heap layout is required.\nPR:N - READDIR on a guest/anonymous ksmbd share or AUTH_SYS NFS export needs no host account or capability. Automount of a malicious volume by udisks2/systemd also requires no attacker privileges on the victim.\nUI:N - Once the crafted or inline-data ext4 volume is exported or automounted, the attacker alone issues NFS/SMB READDIR or local getdents64. No separate victim must open a file or confirm a dialog at attack time.\nS:U - The out-of-bounds read and any resulting kernel crash stay within the host kernel's security authority. This is not a VM escape, IOMMU/DMA bypass, or other cross-boundary breakout.\nC:H - ext4_check_dir_entry over-reads de->rec_len and adjacent dirent fields past the inline kmalloc buffer. If the inflated extra_size bound lets the check pass, dir_emit copies de->name for up to 255 bytes of adjacent kernel heap into the getdents/NFS/SMB reply.\nI:N - The defect is an over-read on the readdir path only. ext4_read_inline_dir does not write the over-read dirent, and there is no out-of-bounds write, type confusion, or control-flow hijack primitive.\nA:H - KASAN reports a slab-out-of-bounds read in __ext4_check_dir_entry. An over-read that reaches unmapped slab or guard pages oopses or panics the kernel, and the attacker can repeat READDIR/getdents against the crafted directory." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ext4/inline.c" ], "versions": [ { "version": "c4d8b0235aa98f8c26bf94d308be3fdd24154572", "lessThan": "d1e7c186555ad65554fd2f2b02f5a539aa35ae48", "status": "affected", "versionType": "git" }, { "version": "c4d8b0235aa98f8c26bf94d308be3fdd24154572", "lessThan": "5fd20d4e50dd6e460b3ea8e4396f8553d4526f8f", "status": "affected", "versionType": "git" }, { "version": "c4d8b0235aa98f8c26bf94d308be3fdd24154572", "lessThan": "1a1dea633b724a1c042dbcdb1fed27f410916688", "status": "affected", "versionType": "git" }, { "version": "c4d8b0235aa98f8c26bf94d308be3fdd24154572", "lessThan": "b060861f662d4826dc700a1c3584243bb3474cfe", "status": "affected", "versionType": "git" }, { "version": "c4d8b0235aa98f8c26bf94d308be3fdd24154572", "lessThan": "6702c7da86d8cdb88d0fc57166286e115ffeb8c0", "status": "affected", "versionType": "git" }, { "version": "c4d8b0235aa98f8c26bf94d308be3fdd24154572", "lessThan": "36bf17bb90cdf7a623499b624b05acde4d2feef5", "status": "affected", "versionType": "git" }, { "version": "c4d8b0235aa98f8c26bf94d308be3fdd24154572", "lessThan": "9333cc809f0a89e001b814155a6cb8903a6274df", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/ext4/inline.c" ], "versions": [ { "version": "3.10", "status": "affected" }, { "version": "0", "lessThan": "3.10", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.221", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.188", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.157", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.110", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.52", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.6", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "5.15.221" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "6.1.188" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "6.6.157" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "6.12.110" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "6.18.52" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "7.2.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/d1e7c186555ad65554fd2f2b02f5a539aa35ae48" }, { "url": "https://git.kernel.org/stable/c/5fd20d4e50dd6e460b3ea8e4396f8553d4526f8f" }, { "url": "https://git.kernel.org/stable/c/1a1dea633b724a1c042dbcdb1fed27f410916688" }, { "url": "https://git.kernel.org/stable/c/b060861f662d4826dc700a1c3584243bb3474cfe" }, { "url": "https://git.kernel.org/stable/c/6702c7da86d8cdb88d0fc57166286e115ffeb8c0" }, { "url": "https://git.kernel.org/stable/c/36bf17bb90cdf7a623499b624b05acde4d2feef5" }, { "url": "https://git.kernel.org/stable/c/9333cc809f0a89e001b814155a6cb8903a6274df" } ], "title": "ext4: fix out-of-bounds read in ext4_read_inline_dir()", "x_generator": { "engine": "bippy-1.2.0" } } } }