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High

Use-after-free in Linux kernel i915 intel_engine_park_heartbeat

IdentifiersCVE-2026-31656CWE-416

CVE-2026-31656 is a race-condition vulnerability in the Linux kernel's drm/i915/gt subsystem, specifically involving heartbeat handling in intel_engine_park_heartbeat(). The flaw arises because the heartbeat worker and intel_engine_park_heartbeat() can concurrently release the same engine->heartbeat.systole request. In the vulnerable logic, the heartbeat worker reads engine->heartbeat.systole and later clears the pointer in a separate, non-atomic step after calling i915_request_put(). If, on another CPU, request retirement drops the engine wakeref to zero and triggers __engine_park() -> intel_engine_park_heartbeat(), and the heartbeat timer is still pending, intel_engine_park_heartbeat() may observe the stale non-NULL systole pointer and call i915_request_put() on the same request a second time. This can cause a refcount underflow and result in a use-after-free condition. The upstream fix replaces the separate read-and-clear operations with atomic xchg() in both racing paths so only one caller can obtain and release the pointer.

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ANALYST BRIEF

Impact, mitigation & remediation

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Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can trigger a kernel-space use-after-free and refcount underflow in the i915 graphics driver path. The practical impact includes kernel instability, warnings from refcount protection, crashes, and potentially undefined behavior affecting confidentiality, integrity, and availability. Published CVSS vectors characterize the issue as locally exploitable with low privileges and high impact to C, I, and A.

Mitigation

If you can’t patch tonight, do this now.

No specific temporary workaround is provided in the supplied content. If immediate patching is not possible, the only defensible mitigation based on available information is to minimize exposure by restricting use of affected vulnerable kernel builds and prioritizing updates on systems using the i915 DRM driver. Long-term mitigation is patching; the information currently available does not provide a reliable configuration-only workaround.

Remediation

Patch, then assume compromise.

Update to a Linux kernel release that includes the drm/i915/gt fix for CVE-2026-31656. The remediation is to use the patched code that replaces the non-atomic pointer read plus separate clear with atomic xchg() in the competing heartbeat-release paths. The referenced upstream fix was cherry-picked from commit 13238dc0ee4f9ab8dafa2cca7295736191ae2f42. Vendor kernel updates from SUSE and other distributors that include this patch should be applied, followed by a reboot into the fixed kernel.
PUBLIC EXPLOITS

Exploits

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VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

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VendorProductType
LinuxLinux Kerneloperating_system

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ACTIVITY FEED

Recent activity

6 sources tracked across advisories and community write-ups. News coverage will land here when it surfaces.

No news coverage yet. Advisories and community discussion only.

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Threat actor evidence

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Associated malware

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Detection signatures

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Social activity2

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