Local XFS data disclosure via incorrect preallocation
Published Aug 24, 2022 · Updated Aug 3, 2024
Information disclosure in Linux Kernel before 5.16 allows local users to read inaccessible XFS data through XFS_IOC_ALLOCSP. The xfs_ioc_space path grows an unaligned file past EOF with allocation type 0, exposing existing block contents instead of mapping them as unwritten preallocation. A low-privileged local account must invoke the legacy ioctl on a file in an XFS filesystem; the consequence is disclosure of otherwise unreadable filesystem data.
Summary
What happened
Information disclosure in Linux Kernel before 5.16 allows local users to read inaccessible XFS data through XFS_IOC_ALLOCSP. The xfs_ioc_space path grows an unaligned file past EOF with allocation type 0, exposing existing block contents instead of mapping them as unwritten preallocation. A low-privileged local account must invoke the legacy ioctl on a file in an XFS filesystem; the consequence is disclosure of otherwise unreadable filesystem data.
The record
- CVE
- CVE-2021-4155
- Published
- Aug 24, 2022
- Updated
- Aug 3, 2024
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- CWE-131, T1005
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Aug 24, 2022CVE publishedPublication date reported by the CVE source.
- Aug 3, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=Fixed in Kernel v5.16
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- XFS_IOC_ALLOCSP xfs_test proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo