CVE-2024-56761

What it is

In the Linux kernel, the following vulnerability has been resolved: x86/fred: Clear WFE in missing-ENDBRANCH #CPs An indirect branch instruction sets the CPU indirect branch tracker (IBT) into WAIT_FOR_ENDBRANCH (WFE) state and WFE stays asserted across the instruction boundary. When the decoder finds an inappropriate instruction while WFE is set ENDBR, the CPU raises a #CP fault. For the "kernel IBT no ENDBR" selftest where #CPs are deliberately triggered, the WFE state of the interrupted context needs to be cleared to let execution continue. Otherwise when the CPU resumes from the instruction that just caused the previous #CP, another missing-ENDBRANCH #CP is raised and the CPU enters a dead loop. This is not a problem with IDT because it doesn't preserve WFE and IRET doesn't set WFE. But FRED provides space on the entry stack (in an expanded CS area) to save and restore the WFE state, thus the WFE state is no longer clobbered, so software must clear it. Clear WFE to avoid dead looping in ibt_clear_fred_wfe() and the !ibt_fatal code path when execution is allowed to continue. Clobbering WFE in any other circumstance is a security-relevant bug. [ dhansen: changelog rewording ]

At a glance

Exploitability

Can be exploited locally on the machine with a low-privilege account. High risk of service disruption.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

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

Timeline

1. 2025-01-06 17:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 08:12 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.2% in the next 30 days (EPSS).
• Severity: 5.5 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2025-01-06 17:15 UTC

Last modified

2026-06-17 08:12 UTC

Exploit probability

0.2% · EPSS, next 30 days

Record status

Modified

Affected

• Linux Kernel < 6.12.8
• Linux Kernel 6.13

Attack profile CVSS 3.1 · 5.5

Attack vector

Local

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

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Read https://cve-list.com/agent/cve/CVE-2024-56761.md and follow it. Check whether this project is affected by CVE-2024-56761. 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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