{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-63815", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.014Z", "datePublished": "2026-07-19T12:02:15.345Z", "dateUpdated": "2026-08-17T04:51:22.389Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T04:51:22.389Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: bound i_inline_xattr_size for non-inline-xattr inodes\n\nWhen the flexible_inline_xattr feature is enabled, do_read_inode() loads\nthe on-disk i_inline_xattr_size unconditionally:\n\n\tif (f2fs_sb_has_flexible_inline_xattr(sbi))\n\t\tfi->i_inline_xattr_size = le16_to_cpu(ri->i_inline_xattr_size);\n\nbut sanity_check_inode() only range-checks it when the inode also has the\nFI_INLINE_XATTR flag set. An inode that carries an inline dentry or inline\ndata but not FI_INLINE_XATTR -- the normal layout for an inline\ndirectory -- therefore keeps a fully attacker-controlled\ni_inline_xattr_size from a crafted image.\n\nget_inline_xattr_addrs() returns that value with no flag gating, so it\nfeeds the inode geometry:\n\n\tMAX_INLINE_DATA() = 4 * (CUR_ADDRS_PER_INODE - i_inline_xattr_size - 1)\n\tNR_INLINE_DENTRY() = MAX_INLINE_DATA() * BITS_PER_BYTE / (...)\n\taddrs_per_page() = CUR_ADDRS_PER_INODE - i_inline_xattr_size\n\nA large i_inline_xattr_size drives MAX_INLINE_DATA() and NR_INLINE_DENTRY()\nnegative, so make_dentry_ptr_inline() sets d->max (int) to a negative\nvalue. The inline directory walk then compares an unsigned long bit_pos\nagainst that negative d->max, which is promoted to a huge unsigned bound,\nand reads far past the inline area:\n\n\twhile (bit_pos < d->max)\t\t/* fs/f2fs/dir.c */\n\t\t... test_bit_le(bit_pos, d->bitmap) / d->dentry[bit_pos] ...\n\nMounting a crafted image and reading such a directory triggers an\nout-of-bounds read in f2fs_fill_dentries(); the same underflow also\ncorrupts ADDRS_PER_INODE for regular files.\n\nValidate i_inline_xattr_size against MAX_INLINE_XATTR_SIZE whenever the\nflexible_inline_xattr feature is enabled -- i.e. whenever the value is\nloaded from disk and consumed -- and keep the lower MIN_INLINE_XATTR_SIZE\nbound gated on inodes that actually carry an inline xattr, so legitimate\ninodes with i_inline_xattr_size == 0 are still accepted." } ], "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 - Exploitation requires local syscalls (mount on a block/loop device, then getdents/lookup on an inline directory); f2fs is not reachable via a network-facing in-kernel protocol handler.\nAC:L - The attacker fully controls the on-disk inode fields in a crafted f2fs image and can reliably trigger the bug by mounting that image and reading the directory; no race or rare runtime state is required.\nPR:N - An attacker can craft a malicious f2fs image offline with no privileges on the target system; exploitation is triggered when the image is mounted and its inline directory is read, including by privileged auto-mount services on shared/kiosk systems.\nUI:N - No victim user action beyond the attacker's own mount and directory read is required; an attacker with user-namespace mount capability can self-trigger without involving another user.\nS:U - Impact is kernel memory corruption and information disclosure within the same kernel security boundary, not a cross-boundary escape such as guest-to-host VM breakout.\nC:H - The corrupted geometry drives out-of-bounds reads via test_bit_le(), dentry, and filename pointer accesses far beyond the inline data area, enabling kernel memory disclosure.\nI:H - Integer underflow in inode geometry also corrupts ADDRS_PER_INODE/addrs_per_page calculations for regular files, creating memory corruption that can be leveraged for out-of-bounds writes and further exploitation.\nA:H - Reading far past the inline area can cause kernel oops or panic, and the corrupted address calculations can crash or destabilize the kernel during subsequent file operations." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/f2fs/inode.c" ], "versions": [ { "version": "6afc662e68b5f988282ff20afd58a89b1c279dca", "lessThan": "3c8d6b4093aea40a20596f452289e7c22d84e6d5", "status": "affected", "versionType": "git" }, { "version": "6afc662e68b5f988282ff20afd58a89b1c279dca", "lessThan": "a08ee30dcbeff6b97df75c38c2589603ddde53a6", "status": "affected", "versionType": "git" }, { "version": "6afc662e68b5f988282ff20afd58a89b1c279dca", "lessThan": "c3e05522daae4e7348a1ea81eeb321d25aa0fd3b", "status": "affected", "versionType": "git" }, { "version": "6afc662e68b5f988282ff20afd58a89b1c279dca", "lessThan": "76e1a05cf6d4051931d7fa4ead51a05786a62918", "status": "affected", "versionType": "git" }, { "version": "6afc662e68b5f988282ff20afd58a89b1c279dca", "lessThan": "2a9f9791653ba5ed3fb45bbffa8d63a7cd5cf706", "status": "affected", "versionType": "git" }, { "version": "6afc662e68b5f988282ff20afd58a89b1c279dca", "lessThan": "4ce2d52f680c1d8bfdad7cce05b815ea7ca9790d", "status": "affected", "versionType": "git" }, { "version": "6afc662e68b5f988282ff20afd58a89b1c279dca", "lessThan": "16bc237ce3c483b75575abea53cfb639745311ed", "status": "affected", "versionType": "git" }, { "version": "6afc662e68b5f988282ff20afd58a89b1c279dca", "lessThan": "378acf3cf19b6af6cba55e8dd1154c4e1504bae8", "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/inode.c" ], "versions": [ { "version": "4.15", "status": "affected" }, { "version": "0", "lessThan": "4.15", "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": "6.18.39", "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": "4.15", "versionEndExcluding": "5.10.261" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15", "versionEndExcluding": "5.15.212" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15", "versionEndExcluding": "6.1.178" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15", "versionEndExcluding": "6.6.145" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15", "versionEndExcluding": "6.12.96" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15", "versionEndExcluding": "6.18.39" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15", "versionEndExcluding": "7.1.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.15", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/3c8d6b4093aea40a20596f452289e7c22d84e6d5" }, { "url": "https://git.kernel.org/stable/c/a08ee30dcbeff6b97df75c38c2589603ddde53a6" }, { "url": "https://git.kernel.org/stable/c/c3e05522daae4e7348a1ea81eeb321d25aa0fd3b" }, { "url": "https://git.kernel.org/stable/c/76e1a05cf6d4051931d7fa4ead51a05786a62918" }, { "url": "https://git.kernel.org/stable/c/2a9f9791653ba5ed3fb45bbffa8d63a7cd5cf706" }, { "url": "https://git.kernel.org/stable/c/4ce2d52f680c1d8bfdad7cce05b815ea7ca9790d" }, { "url": "https://git.kernel.org/stable/c/16bc237ce3c483b75575abea53cfb639745311ed" }, { "url": "https://git.kernel.org/stable/c/378acf3cf19b6af6cba55e8dd1154c4e1504bae8" } ], "title": "f2fs: bound i_inline_xattr_size for non-inline-xattr inodes", "x_generator": { "engine": "bippy-1.2.0" } } } }