FKIE_CVE-2026-63818
Vulnerability from fkie_nvd - Published: 2026-07-19 12:16 - Updated: 2026-08-17 05:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved:
f2fs: validate orphan inode entry count
f2fs_recover_orphan_inodes() trusts the orphan block entry_count when
replaying orphan inodes from the checkpoint pack. A corrupted entry_count
larger than F2FS_ORPHANS_PER_BLOCK makes the recovery loop read past the
ino[] array and interpret footer or following data as inode numbers.
On a crafted image, mounting an unpatched kernel can drive orphan recovery
into f2fs_bug_on() and panic the kernel. Validate entry_count before
consuming entries so corrupted checkpoint data fails the mount with
-EFSCORRUPTED and requests fsck instead.
Set ERROR_INCONSISTENT_ORPHAN as well, so the corruption reason can be
recorded in the superblock s_errors[] field. This gives fsck a persistent
hint even though mount-time orphan recovery failure may leave no chance to
persist SBI_NEED_FSCK through a checkpoint.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/f2fs/checkpoint.c",
"include/linux/f2fs_fs.h"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "210c210c92d78fdf5051bc55c5c69044b1a2150a",
"status": "affected",
"version": "127e670abfa7fa150f6550d620ded930f5bdb4e7",
"versionType": "git"
},
{
"lessThan": "ad101d15716f5a24d1fa82a849f80430c805a3dd",
"status": "affected",
"version": "127e670abfa7fa150f6550d620ded930f5bdb4e7",
"versionType": "git"
},
{
"lessThan": "d18c81f5d0ecd5796aa47d66d98f2dd54d8d0f70",
"status": "affected",
"version": "127e670abfa7fa150f6550d620ded930f5bdb4e7",
"versionType": "git"
},
{
"lessThan": "d2f236196d542ccd8505736e41c3a1d3f0305f6f",
"status": "affected",
"version": "127e670abfa7fa150f6550d620ded930f5bdb4e7",
"versionType": "git"
},
{
"lessThan": "550511a2470f6d204fa07b331f048bd2d3c51280",
"status": "affected",
"version": "127e670abfa7fa150f6550d620ded930f5bdb4e7",
"versionType": "git"
},
{
"lessThan": "8aad54746c251f2c2370118df766c0c82e2d2091",
"status": "affected",
"version": "127e670abfa7fa150f6550d620ded930f5bdb4e7",
"versionType": "git"
},
{
"lessThan": "2e12381d4495dc8b0ff042c6856022b2e359835c",
"status": "affected",
"version": "127e670abfa7fa150f6550d620ded930f5bdb4e7",
"versionType": "git"
},
{
"lessThan": "846c499a65816d13f1186e3090e825e8bb8bcb8b",
"status": "affected",
"version": "127e670abfa7fa150f6550d620ded930f5bdb4e7",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"fs/f2fs/checkpoint.c",
"include/linux/f2fs_fs.h"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "3.8"
},
{
"lessThan": "3.8",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.261",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.212",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.178",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.145",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.96",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.38",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.3",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"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."
}
],
"id": "CVE-2026-63818",
"lastModified": "2026-08-17T05:17:19.143",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 8.4,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 2.5,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-07-19T12:16:54.873",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/210c210c92d78fdf5051bc55c5c69044b1a2150a"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/2e12381d4495dc8b0ff042c6856022b2e359835c"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/550511a2470f6d204fa07b331f048bd2d3c51280"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/846c499a65816d13f1186e3090e825e8bb8bcb8b"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/8aad54746c251f2c2370118df766c0c82e2d2091"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/ad101d15716f5a24d1fa82a849f80430c805a3dd"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/d18c81f5d0ecd5796aa47d66d98f2dd54d8d0f70"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/d2f236196d542ccd8505736e41c3a1d3f0305f6f"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Awaiting Analysis"
}
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Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- Confirmed: The vulnerability has been validated from an analyst's perspective.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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