Linux Kernel up to 6.19.12 intel_engine_park_heartbeat use after free

CVSS Meta Temp Score
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CTI Interest Score
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7.7$0-$5k0.00

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.19.12 and classified as critical. This impacts the function intel_engine_park_heartbeat. The manipulation results in use after free. This vulnerability is reported as CVE-2026-31656. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.19.12. It has been classified as critical. Affected is the function intel_engine_park_heartbeat. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: drm/i915/gt: fix refcount underflow in intel_engine_park_heartbeat A use-after-free / refcount underflow is possible when the heartbeat worker and intel_engine_park_heartbeat() race to release the same engine->heartbeat.systole request. The heartbeat worker reads engine->heartbeat.systole and calls i915_request_put() on it when the request is complete, but clears the pointer in a separate, non-atomic step. Concurrently, a request retirement on another CPU can drop the engine wakeref to zero, triggering __engine_park() -> intel_engine_park_heartbeat(). If the heartbeat timer is pending at that point, cancel_delayed_work() returns true and intel_engine_park_heartbeat() reads the stale non-NULL systole pointer and calls i915_request_put() on it again, causing a refcount underflow: ``` <4> [487.221889] Workqueue: i915-unordered engine_retire [i915] <4> [487.222640] RIP: 0010:refcount_warn_saturate+0x68/0xb0 ... <4> [487.222707] Call Trace: <4> [487.222711] <TASK> <4> [487.222716] intel_engine_park_heartbeat.part.0+0x6f/0x80 [i915] <4> [487.223115] intel_engine_park_heartbeat+0x25/0x40 [i915] <4> [487.223566] __engine_park+0xb9/0x650 [i915] <4> [487.223973] ____intel_wakeref_put_last+0x2e/0xb0 [i915] <4> [487.224408] __intel_wakeref_put_last+0x72/0x90 [i915] <4> [487.224797] intel_context_exit_engine+0x7c/0x80 [i915] <4> [487.225238] intel_context_exit+0xf1/0x1b0 [i915] <4> [487.225695] i915_request_retire.part.0+0x1b9/0x530 [i915] <4> [487.226178] i915_request_retire+0x1c/0x40 [i915] <4> [487.226625] engine_retire+0x122/0x180 [i915] <4> [487.227037] process_one_work+0x239/0x760 <4> [487.227060] worker_thread+0x200/0x3f0 <4> [487.227068] ? __pfx_worker_thread+0x10/0x10 <4> [487.227075] kthread+0x10d/0x150 <4> [487.227083] ? __pfx_kthread+0x10/0x10 <4> [487.227092] ret_from_fork+0x3d4/0x480 <4> [487.227099] ? __pfx_kthread+0x10/0x10 <4> [487.227107] ret_from_fork_asm+0x1a/0x30 <4> [487.227141] </TASK> ``` Fix this by replacing the non-atomic pointer read + separate clear with xchg() in both racing paths. xchg() is a single indivisible hardware instruction that atomically reads the old pointer and writes NULL. This guarantees only one of the two concurrent callers obtains the non-NULL pointer and performs the put, the other gets NULL and skips it. (cherry picked from commit 13238dc0ee4f9ab8dafa2cca7295736191ae2f42)

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2026-31656 since 03/09/2026. The exploitability is told to be easy. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 06/04/2026).

The vulnerability scanner Nessus provides a plugin with the ID 310316 (Linux Distros Unpatched Vulnerability : CVE-2026-31656), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.15.203, 6.1.169, 6.6.135, 6.12.82, 6.18.23 or 6.19.13 eliminates this vulnerability. Applying the patch 70d3e622b10092fc483e28e57b4e8c49d9cc7f68/8ce44d28a84fd5e053a88b04872a89d95c0779d4/ca3f48c3567dd49efdc55b80029ae74659c682ee/a00e92bf6583d019a4fb2c2df7007e6c9b269ce7/2af8b200cae3fdd0e917ecc2753b28bb40c876c1/455d98ed527fc94eed90406f90ab2391464ca657/4c71fd099513bfa8acab529b626e1f0097b76061 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (310316) and EUVD (EUVD-2026-25549). Once again VulDB remains the best source for vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.9
VulDB Meta Temp Score: 7.7

VulDB Base Score: 8.0
VulDB Temp Score: 7.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.8
CNA Vector (Linux): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 310316
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-31656

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.15.203/6.1.169/6.6.135/6.12.82/6.18.23/6.19.13
Patch: 70d3e622b10092fc483e28e57b4e8c49d9cc7f68/8ce44d28a84fd5e053a88b04872a89d95c0779d4/ca3f48c3567dd49efdc55b80029ae74659c682ee/a00e92bf6583d019a4fb2c2df7007e6c9b269ce7/2af8b200cae3fdd0e917ecc2753b28bb40c876c1/455d98ed527fc94eed90406f90ab2391464ca657/4c71fd099513bfa8acab529b626e1f0097b76061

Timelineinfo

03/09/2026 CVE reserved
04/24/2026 +45 days Advisory disclosed
04/24/2026 +0 days VulDB entry created
06/04/2026 +41 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-31656 (🔒)
GCVE (CVE): GCVE-0-2026-31656
GCVE (VulDB): GCVE-100-359412
EUVD: 🔒

Entryinfo

Created: 04/24/2026 17:59
Updated: 06/04/2026 05:06
Changes: 04/24/2026 17:59 (58), 04/24/2026 18:34 (1), 04/26/2026 13:00 (2), 06/04/2026 05:06 (12)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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