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High 8.4

Vulnerability in Linux kernel

CVE-2026-63815 First seen on SecPulse

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-63815 has been found in Linux kernel.
Successful exploitation can lead to full system takeover. CVSS score: 8.4/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-63815" on the vendor's site.

CVE-2026-63815 (Linux kernel) — CVSS v3 8.4
Attack vector: local / unauthenticated / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

What is the problem

A vulnerability (unclassified) exists in Linux kernel.

Affected scope

Check the vendor advisory for the affected versions of Linux kernel.

Severity

Severity: High (CVSS 8.4/10). Successful exploitation can lead to full system takeover.

How to fix

Update to the patched release per vendor advisory.

Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposureidentify
    Audit SBOM/dependencies for affected components.

    資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。

  2. 2
    Post-deployment verificationverify
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

EcosystemPackageAffectedFixed
Linux Kernel
≥ 4.15.0, < 5.10.261
≥ 5.11.0, < 5.15.212
≥ 5.16.0, < 6.1.178
≥ 6.2.0, < 6.6.145
≥ 6.7.0, < 6.12.96
≥ 6.13.0, < 6.18.39
+1 more
5.10.261
5.15.212
6.1.178
6.6.145
6.12.96
6.18.39

Fix status by distribution

Fixed packages published by each distribution for this CVE

Original description The description as published by the source.

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…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

References

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