CVE-2026-63815

What it is

In the Linux kernel, the following vulnerability has been resolved: f2fs: bound i_inline_xattr_size for non-inline-xattr inodes When the flexible_inline_xattr feature is enabled, do_read_inode() loads the on-disk i_inline_xattr_size unconditionally: if (f2fs_sb_has_flexible_inline_xattr(sbi)) fi->i_inline_xattr_size = le16_to_cpu(ri->i_inline_xattr_size); but sanity_check_inode() only range-checks it when the inode also has the FI_INLINE_XATTR flag set. An inode that carries an inline dentry or inline data but not FI_INLINE_XATTR -- the normal layout for an inline directory -- therefore keeps a fully attacker-controlled i_inline_xattr_size from a crafted image. get_inline_xattr_addrs() returns that value with no flag gating, so it feeds the inode geometry: MAX_INLINE_DATA() = 4 * (CUR_ADDRS_PER_INODE - i_inline_xattr_size - 1) NR_INLINE_DENTRY() = MAX_INLINE_DATA() * BITS_PER_BYTE / (...) addrs_per_page() = CUR_ADDRS_PER_INODE - i_inline_xattr_size A large i_inline_xattr_size drives MAX_INLINE_DATA() and NR_INLINE_DENTRY() negative, so make_dentry_ptr_inline() sets d->max (int) to a negative value. The inline directory walk then compares an unsigned long bit_pos against that negative d->max, which is promoted to a huge unsigned bound, and reads far past the inline area: while (bit_pos < d->max) /* fs/f2fs/dir.c */ ... test_bit_le(bit_pos, d->bitmap) / d->dentry[bit_pos] ... Mounting a crafted image and reading such a directory triggers an out-of-bounds read in f2fs_fill_dentries(); the same underflow also corrupts ADDRS_PER_INODE for regular files. Validate i_inline_xattr_size against MAX_INLINE_XATTR_SIZE whenever the flexible_inline_xattr feature is enabled -- i.e. whenever the value is loaded from disk and consumed -- and keep the lower MIN_INLINE_XATTR_SIZE bound gated on inodes that actually carry an inline xattr, so legitimate inodes with i_inline_xattr_size == 0 are still accepted.

At a glance

Exploitability

Can be exploited locally on the machine without logging in. High risk of data exposure, data tampering, service disruption.

Exploit odds

0.1% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-07-19 07:54 UTC ReservedThe CVE id was reserved by its CNA
2. 2026-07-19 12:16 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-11-10 20:43 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.1% in the next 30 days (EPSS).
• Severity: 8.4 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-07-19 12:16 UTC

Last modified

2026-11-10 20:43 UTC

Exploit probability

0.1% · EPSS, next 30 days

Weakness

CWE-125 · Out-of-bounds read

Record status

Analyzed

Affected

• Linux Kernel < 5.10.261
• Linux Kernel < 5.15.212
• Linux Kernel < 6.1.178
• Linux Kernel < 6.6.145
• Linux Kernel < 6.12.96
• Linux Kernel < 6.18.39
• Linux Kernel < 7.1.3

Attack profile CVSS 3.1 · 8.4

Attack vector

Local

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Is it in your code?

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Read https://cve-list.com/agent/cve/CVE-2026-63815.md and follow it. Check whether this project is affected by CVE-2026-63815. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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