{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-63818", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.014Z", "datePublished": "2026-07-19T12:02:17.022Z", "dateUpdated": "2026-08-17T04:51:25.680Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T04:51:25.680Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: validate orphan inode entry count\n\nf2fs_recover_orphan_inodes() trusts the orphan block entry_count when\nreplaying orphan inodes from the checkpoint pack. A corrupted entry_count\nlarger than F2FS_ORPHANS_PER_BLOCK makes the recovery loop read past the\nino[] array and interpret footer or following data as inode numbers.\n\nOn a crafted image, mounting an unpatched kernel can drive orphan recovery\ninto f2fs_bug_on() and panic the kernel. Validate entry_count before\nconsuming entries so corrupted checkpoint data fails the mount with\n-EFSCORRUPTED and requests fsck instead.\n\nSet ERROR_INCONSISTENT_ORPHAN as well, so the corruption reason can be\nrecorded in the superblock s_errors[] field. This gives fsck a persistent\nhint even though mount-time orphan recovery failure may leave no chance to\npersist SBI_NEED_FSCK through a checkpoint." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.4, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable code runs only during F2FS mount via the mount syscall path (fs_context → get_tree_bdev → f2fs_fill_super → f2fs_recover_orphan_inodes); it is not reachable from network protocols or device drivers.\nAC:L - An attacker fully controls the crafted on-disk orphan block including entry_count and ino[] contents, so triggering the bug is reliable once a victim or privileged auto-mount path mounts the image; no race or rare layout dependency is required.\nPR:N - The attacker needs no privileges on the victim system—only a malicious F2FS image delivered via removable media, downloaded disk image, or similar that a privileged mount/auto-mount daemon later processes.\nUI:N - No victim interaction is required when the attacker mounts their own crafted image (e.g., loop mount in a user namespace with CAP_SYS_ADMIN), and automated privileged mount paths can process attacker-supplied media without further user action.\nS:U - Impact is confined to kernel/filesystem integrity and availability on the host mounting the image; it does not cross a VM, container, or IOMMU security boundary.\nC:H - The unchecked loop indexes past ino[F2FS_ORPHANS_PER_BLOCK-1] into the block footer and beyond the 4 KiB orphan block, constituting an out-of-bounds read of attacker-influenced metadata that can leak kernel-adjacent memory contents.\nI:H - Misinterpreted inode numbers are passed to recover_orphan_inode(), which clear_nlink() and iput() (truncating data) on matching real inodes, enabling deliberate destruction of filesystem contents from a crafted image.\nA:H - Crafted entry_count values drive f2fs_bug_on() on -ENOENT (kernel BUG/panic with CONFIG_F2FS_CHECK_FS, or WARN/oops otherwise) and can hang or crash the system during mount via unbounded orphan recovery iteration." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/f2fs/checkpoint.c", "include/linux/f2fs_fs.h" ], "versions": [ { "version": "127e670abfa7fa150f6550d620ded930f5bdb4e7", "lessThan": "210c210c92d78fdf5051bc55c5c69044b1a2150a", "status": "affected", "versionType": "git" }, { "version": "127e670abfa7fa150f6550d620ded930f5bdb4e7", "lessThan": "ad101d15716f5a24d1fa82a849f80430c805a3dd", "status": "affected", "versionType": "git" }, { "version": "127e670abfa7fa150f6550d620ded930f5bdb4e7", "lessThan": "d18c81f5d0ecd5796aa47d66d98f2dd54d8d0f70", "status": "affected", "versionType": "git" }, { "version": "127e670abfa7fa150f6550d620ded930f5bdb4e7", "lessThan": "d2f236196d542ccd8505736e41c3a1d3f0305f6f", "status": "affected", "versionType": "git" }, { "version": "127e670abfa7fa150f6550d620ded930f5bdb4e7", "lessThan": "550511a2470f6d204fa07b331f048bd2d3c51280", "status": "affected", "versionType": "git" }, { "version": "127e670abfa7fa150f6550d620ded930f5bdb4e7", "lessThan": "8aad54746c251f2c2370118df766c0c82e2d2091", "status": "affected", "versionType": "git" }, { "version": "127e670abfa7fa150f6550d620ded930f5bdb4e7", "lessThan": "2e12381d4495dc8b0ff042c6856022b2e359835c", "status": "affected", "versionType": "git" }, { "version": "127e670abfa7fa150f6550d620ded930f5bdb4e7", "lessThan": "846c499a65816d13f1186e3090e825e8bb8bcb8b", "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/f2fs/checkpoint.c", "include/linux/f2fs_fs.h" ], "versions": [ { "version": "3.8", "status": "affected" }, { "version": "0", "lessThan": "3.8", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.261", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.212", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.178", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.145", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.96", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.38", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.3", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "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": "3.8", "versionEndExcluding": "5.10.261" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.8", "versionEndExcluding": "5.15.212" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.8", "versionEndExcluding": "6.1.178" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.8", "versionEndExcluding": "6.6.145" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.8", "versionEndExcluding": "6.12.96" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.8", "versionEndExcluding": "6.18.38" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.8", "versionEndExcluding": "7.1.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.8", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/210c210c92d78fdf5051bc55c5c69044b1a2150a" }, { "url": "https://git.kernel.org/stable/c/ad101d15716f5a24d1fa82a849f80430c805a3dd" }, { "url": "https://git.kernel.org/stable/c/d18c81f5d0ecd5796aa47d66d98f2dd54d8d0f70" }, { "url": "https://git.kernel.org/stable/c/d2f236196d542ccd8505736e41c3a1d3f0305f6f" }, { "url": "https://git.kernel.org/stable/c/550511a2470f6d204fa07b331f048bd2d3c51280" }, { "url": "https://git.kernel.org/stable/c/8aad54746c251f2c2370118df766c0c82e2d2091" }, { "url": "https://git.kernel.org/stable/c/2e12381d4495dc8b0ff042c6856022b2e359835c" }, { "url": "https://git.kernel.org/stable/c/846c499a65816d13f1186e3090e825e8bb8bcb8b" } ], "title": "f2fs: validate orphan inode entry count", "x_generator": { "engine": "bippy-1.2.0" } } } }