Executive brief
The Linux kernel's ext2 file system implementation had a flaw where inode metadata updates could be silently lost for files flagged with the IS_SYNC attribute (used to ensure synchronous writes). The bug affected the ext2_setsize() and ext2_xattr_set2() functions, which could fail to persist critical file metadata changes to disk, potentially leading to data corruption or loss upon system failure.
Technical details
The vulnerability is a logic error in the ext2 file system code where the conditional check for IS_SYNC inodes was inverted. The vulnerable code called sync_inode_metadata() only when IS_SYNC was set, but sync_inode_metadata() requires the inode to already be marked dirty to perform any action. If the inode was not yet marked dirty, the synchronization would be skipped, causing inode updates to be lost. The fix unconditionally marks the inode dirty first, then conditionally calls sync_inode_metadata() for IS_SYNC inodes. The defect affected ext2_setsize() (file truncation) and ext2_xattr_set2() (extended attributes) in Linux kernel versions across a wide range of releases. The fix has been committed and backported to stable kernel branches.
Affected products
- Linux Linux kernel Multiple versions from 2.6.11 through 7.2.y
Timeline
- 2026-09-11: disclosed: CVE-2026-89601 published
- 2026-07-27: patched: Fix committed upstream (commit 356984d1a5c32e94810cbb6c8dc7d8ff2d4d919a)
- 2026-09-07: patched: Fix backported to stable kernel branches