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VulnerabilityAwaiting classification

CVE-2026-63818

HIGH · 8.4 CVSS v3.1 Developing Published 2026-07-19
No fix yet
No fix has been published. The vendor has not shipped a fixed release or patch. You remain exposed.
See remediation →
89/100
Remediation priority · High
No privileges Zero-click 5 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · low confidence
Developing — this CVE was published recently and its authoritative NVD entry is still being established, so we're holding a technical summary until the source data settles rather than publish something unreliable. Re-checking after 2026-08-02.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Recommended fix Moderate confidence

Linux kernel version containing commit 'f2fs: validate orphan inode entry count' - check kernel.org or your distribution's kernel repository for the specific version

  1. Upgrade the Linux kernel to a version that includes the f2fs fix for CVE-2026-63818
  2. The fix adds validation in f2fs_recover_orphan_inodes() to check entry_count against F2FS_ORPHANS_PER_BLOCK before processing orphan inodes
  3. If an image has corrupted entry_count larger than F2FS_ORPHANS_PER_BLOCK, the mount will fail with -EFSCORRUPTED instead of panicking
  4. Run fsck.f2fs on affected filesystems to repair corruption after upgrading the kernel
Caveat None - this is a defensive fix that prevents kernel panic; filesystems with corrupted checkpoint data will need fsck repair

Generated from the published advisory — verify against the referenced sources before acting.

No vendor fix exists The vendor has not published a patch for this.

There is no version to upgrade to and no patch to apply. Every affected install stays exposed until the vendor ships a fix — or somebody else builds one.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-63818 in production — separate from our analysis above.

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