CVE-2024-2193: CPU Speculative Race Condition Vulnerability

CVE-2024-2193 Overview

CVE-2024-2193, publicly known as GhostRace, is a Speculative Race Condition (SRC) vulnerability affecting modern CPU architectures that support speculative execution. The flaw is related to Spectre v1 and was disclosed by VUSEC researchers in coordination with IBM, AMD, and the Xen Project. An attacker with local access can exploit speculative execution paths combined with race conditions to leak arbitrary data from CPU memory. The vulnerability is classified under [CWE-362] (Concurrent Execution using Shared Resource with Improper Synchronization). Affected vendors include AMD, the Linux kernel, and Xen hypervisor.

Critical Impact
An authenticated local attacker can disclose arbitrary kernel or hypervisor memory by racing speculatively-executed critical sections, bypassing synchronization primitives intended to prevent concurrent access to sensitive data.

Affected Products

AMD processors supporting speculative execution (see AMD-SB-7016)
Linux kernel (prior to patch commit 944d5fe50f3f)
Xen hypervisor (per Xen Security Advisory XSA-453)

Discovery Timeline

2024-03-12 - GhostRace research publicly disclosed by VUSEC and IBM
2024-03-15 - CVE-2024-2193 published to NVD
2026-04-15 - Last updated in NVD database

Technical Details for CVE-2024-2193

Vulnerability Analysis

GhostRace demonstrates that common synchronization primitives used in privileged software (kernels, hypervisors) can be transiently bypassed using speculative execution. Synchronization primitives such as spinlocks and mutexes rely on conditional branches to gate access to critical sections. When the CPU mispredicts these branches, it speculatively enters the protected region without acquiring the lock.

During the speculative window, an attacker thread running on a sibling logical core can race to modify shared memory accessed by the speculatively-executed critical section. The result is a speculative race condition that produces transient architectural side effects observable through cache-timing channels.

The attack effectively converts any speculative-execution-vulnerable critical section into a Speculative Concurrent Use-After-Free (SCUAF) primitive, enabling arbitrary information disclosure from kernel address space.

Root Cause

The root cause is the absence of speculative barriers on conditional branches that implement synchronization. The CPU treats lock-acquisition branches like any other branch, allowing speculative execution past the gate. This violates the assumption that mutual exclusion prevents concurrent access in all execution modes, including transient speculative paths [CWE-362].

Attack Vector

Exploitation requires local code execution with the ability to schedule threads onto sibling SMT cores. The attacker primes the branch predictor to force misprediction at a synchronization checkpoint, then races a second thread that mutates shared state during the speculative window. Cache-based side channels recover the leaked data. The VUSEC paper demonstrates extraction of arbitrary kernel memory at approximately 12 KB/s on Linux.

No synthetic exploitation code is reproduced here. Refer to the VUSEC Ghostrace Research Paper and the VUSEC Ghostrace Project for proof-of-concept details.

Detection Methods for CVE-2024-2193

Indicators of Compromise

No reliable host-based IOCs exist; speculative side-channel attacks leave no persistent artifacts in logs or filesystems.
Unexpected high-frequency context switching or thread pinning to specific logical CPUs by unprivileged processes may indicate timing-attack staging.
Anomalous use of sched_setaffinity, perf_event_open, or high-resolution timer APIs by non-administrative processes warrants review.

Detection Strategies

Inventory CPU microcode versions and kernel build IDs to identify hosts running unpatched code paths.
Audit running kernels against the upstream patch commit 944d5fe50f3f and vendor backports referenced in distribution advisories.
Monitor for execution of known GhostRace proof-of-concept binaries by hash, and flag processes that combine CPU affinity calls with cache-flush instructions such as clflush.

Monitoring Recommendations

Track kernel and hypervisor patch deployment across the fleet via configuration-management telemetry.
Alert on local privilege escalation attempts and unusual /dev/cpu/*/msr or /proc/cpuinfo access patterns from low-privilege accounts.
Correlate hardware performance counter anomalies (cache misses, branch mispredictions) with process identity in multi-tenant environments.

How to Mitigate CVE-2024-2193

Immediate Actions Required

Apply the Linux kernel patch introduced in commit 944d5fe50f3f03daacfea16300e656a1691c4a23, which adds an LFENCE serializing instruction inside critical synchronization primitives.
Install Xen updates per Xen Security Advisory XSA-453 on all hypervisor hosts.
Review the AMD Security Bulletin AMD-SB-7016 and follow vendor guidance for affected processor families.
Update Fedora and other Linux distributions using the patched packages referenced in the Fedora Package Announcement.

Patch Information

The upstream Linux fix serializes speculative execution at lock-acquisition sites. Distribution vendors including Fedora have shipped backported kernels. Xen has released hypervisor updates documented in XSA-453. AMD has published microcode and architectural guidance in AMD-SB-7016. See the Linux Kernel Patch for the authoritative commit.

Workarounds

Disable Simultaneous Multi-Threading (SMT/Hyper-Threading) on affected hosts where patches cannot be applied; this eliminates the sibling-core race channel at a performance cost.
Restrict execution of untrusted local code on multi-tenant systems and isolate workloads to dedicated cores using cgroups or CPU pinning.
Limit access to high-resolution timing facilities such as perf_event_open for unprivileged users via kernel.perf_event_paranoid sysctl tuning.

bash

# Restrict unprivileged access to performance counters
sysctl -w kernel.perf_event_paranoid=3
echo 'kernel.perf_event_paranoid=3' >> /etc/sysctl.conf

# Verify kernel includes the GhostRace fix (commit 944d5fe50f3f)
uname -r
rpm -q --changelog kernel | grep -i ghostrace