Kernel memory disclosure via unchecked inline xattr size
Published Jul 19, 2026 · Updated Jul 19, 2026
Out-of-bounds read in Linux Kernel f2fs allows local users to expose kernel memory by mounting and reading a crafted filesystem image. sanity_check_inode() leaves i_inline_xattr_size unbounded on non-inline-xattr inodes, causing f2fs_fill_dentries() to promote a negative directory limit into a huge unsigned walk bound. Exploitation requires local mount capability, flexible_inline_xattr, and a directory read; the same underflow corrupts per-inode address geometry.
Summary
What happened
Out-of-bounds read in Linux Kernel f2fs allows local users to expose kernel memory by mounting and reading a crafted filesystem image. sanity_check_inode() leaves i_inline_xattr_size unbounded on non-inline-xattr inodes, causing f2fs_fill_dentries() to promote a negative directory limit into a huge unsigned walk bound. Exploitation requires local mount capability, flexible_inline_xattr, and a directory read; the same underflow corrupts per-inode address geometry.
The record
- CVE
- CVE-2026-63815
- Published
- Jul 19, 2026
- Updated
- Jul 19, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- Unavailable
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 19, 2026CVE publishedPublication date reported by the CVE source.
- Jul 19, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=4.15
- Affected versionversion=6afc662e68b5f988282ff20afd58a89b1c279dca <16bc237ce3c483b75575abea53cfb639745311ed
- Affected versionversion=6afc662e68b5f988282ff20afd58a89b1c279dca <2a9f9791653ba5ed3fb45bbffa8d63a7cd5cf706
- Affected versionversion=6afc662e68b5f988282ff20afd58a89b1c279dca <378acf3cf19b6af6cba55e8dd1154c4e1504bae8
- Affected versionversion=6afc662e68b5f988282ff20afd58a89b1c279dca <4ce2d52f680c1d8bfdad7cce05b815ea7ca9790d
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
No sourced classifications are available.
Public exploit references
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Technologies
Your stack
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Your stack
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