CVE-2024-26816

What it actually does

When CONFIG_XEN_PV=y, relocations emitted into the .notes section cause the KASLR base address to be written into the world-readable /sys/kernel/notes file, disclosing kernel layout information.

Why it matters to the business

Attackers can obtain kernel memory layout details that simplify bypassing KASLR protections, increasing the likelihood and ease of successful kernel-level exploits across Linux systems using Xen PV mode.

How an attack unfolds

An attacker reads the exposed KASLR base from /sys/kernel/notes, calculates kernel symbol addresses, and leverages the information to bypass address-space randomization in subsequent attacks against other kernel vulnerabilities.

How to fix it

Upgrade the Linux kernel to a version containing commit 13edb509abc91c72152a11baaf0e7c060a312e03 or later; rebuild with the fix applied when CONFIG_XEN_PV is enabled.

How to confirm the fix worked

Confirm the running kernel includes the noted commit or later; verify that values in /sys/kernel/notes match those in System.map and do not reflect KASLR relocation.

Typical attack path

1. Read /sys/kernel/notes to obtain the KASLR base address
2. Calculate kernel symbol locations using the disclosed base
3. Chain the address information into exploitation of another kernel flaw

How to detect it

Monitor for reads of /sys/kernel/notes by unprivileged processes, especially preceding other kernel exploitation attempts; correlate with subsequent privilege-escalation activity.

• /sys/kernel/notes
• startup_xen

What your security team should do

• Apply the kernel fix containing commit 13edb509abc91c72152a11baaf0e7c060a312e03 across all affected systems
• Disable CONFIG_XEN_PV when Xen PV mode is not required
• Review kernel build configurations to ensure .notes section handling prevents information leaks