{"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":"2026-09-16T14:38:36.340Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-16T14:38:36.340Z"},"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-rc1","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-rc1"}]}]}],"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"}}}}