Advisory [CVE-2026-63818] validate orphan inode entry count
This security Red Hat Linux advisory covers CVE-2026-63818.
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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. A flaw was found in the Linux kernel's F2FS (Flash-Friendly File System) component.
This vulnerability arises from improper validation of the orphan inode entry count during the recovery process. A local attacker could craft a malicious F2FS image, which, when mounted on an unpatched system, could lead to a kernel panic, resulting in a Denial of Service (DoS).
The system would become unresponsive, requiring a restart. Red Hat severity: not rated.
Weakness: CWE-125.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 7 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 7 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 7 days ago·verify at source
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