What is the CVSS score of CVE-2026-63974?

CVE-2026-63974 has a contested CVSS base score of 8.8 from a third party (e.g. CISA-ADP), while the vendor rates it High. vuln.today uses the vendor rating as authoritative.

How to fix or mitigate CVE-2026-63974?

Within 24 hours, identify and catalog all Linux systems running kernel versions prior to 6.12.93, 6.18.35, 7.0.12, or 7.1 that have Bluetooth enabled. Within 7 days, begin deployment of patched kernel versions (6.12.93, 6.18.35, 7.0.12, or 7.1 depending on release branch) to systems with active Bluetooth usage. Complete patching of all affected systems within 30 days, and audit Bluetooth configurations to disable the service on systems where it is not operationally required.

Linux Kernel CVE-2026-63974

Q: Which versions of Linux Kernel are affected by CVE-2026-63974?

A kernel vulnerability in the Linux Bluetooth stack (CVE-2026-63974, CVSS 8.8) could allow local attackers to disrupt Bluetooth services or corrupt memory on affected systems; however, no public…. A patch is available.

EUVD-2026-45747 HIGH

Uncontrolled Resource Consumption (CWE-400)

2026-07-19 Linux

GHSA-7hr8-6q2g-wqfg

Denial Of Service Linux

High

Disputed · 8.8 Vendor: Linux

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Gain Bluetooth radio proximity
Delivery

Induce HCI controller reset/close
Exploit

Race timeout work against workqueue drain
Execution

Corrupt teardown state in kernel
Impact

Crash or destabilize host (DoS)

Vulnerability Assessment

Weakness	CWE CWE-400 OWASP Top 10:2025 A06:2025 - Insecure Design ASVS 5.0 V2 - Validation and Business Logic Resource consumption limits MITRE ATT&CK 1 technique across 1 tactic: Impact The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Exploitation Conditions	Requires Bluetooth to be present and active on the target (AV:A - adjacent/RF proximity, not remote internet access), and the attacker must be able to induce the controller reset or hci_dev_close_sync() close path so the vulnerable workqueue-drain window is reached. Limiting factors: the race is timing-dependent (must coincide with the workqueue being drained during reset/close), the attacker needs to be within Bluetooth range, and the flaw only manifests on kernels lacking the HCI_CMD_DRAIN_WORKQUEUE flag on the close path. Per CVSS PR:N/UI:N no authentication or user interaction is required, but the adjacency and timing constraints materially reduce practical exploitability versus the 8.8 score.
Impact	Signals are mixed. The published CVSS 3.1 vector (AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H = 8.8) implies an easily-triggered adjacent attack with full confidentiality, integrity, and availability impact, but this conflicts with the nature of the underlying change - a workqueue-drain race on the reset/close path, which realistically produces a timing-dependent condition rather than a reliable full-compromise primitive. AC:L is questionable for a drain-window race, which typically requires winning a narrow timing window (arguing for AC:H). EPSS is low (0.20%, 10th percentile), there is no KEV listing, and no POC is referenced, all consistent with low real-world exploitation pressure. The 'Information Disclosure' tag also conflicts with the description, which describes no data-leak mechanism - verify with the maintainer. Net assessment: patch as part of normal kernel hygiene, but this is more likely a local/adjacent stability (DoS) hardening fix than an actively weaponizable RCE, despite the high CVSS. Treat the 8.8 as an upper-bound rating pending CWE/impact confirmation.
Exploit ScenarioDerived	An attacker within Bluetooth radio range of a target Linux host repeatedly forces controller resets or close events (for example by manipulating link conditions) to hit the narrow window where the hdev workqueue is being drained while a command timeout is still being queued. Winning this race triggers unstable kernel behavior - a crash or potentially exploitable memory state - during device teardown. No public POC is referenced, and success depends on precise timing.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Jul 20, 2026

Denial-of-service and potential memory-corruption exposure in the Linux kernel Bluetooth stack (hci_sync) arises because hci_dev_close_sync() failed to set the HCI_CMD_DRAIN_WORKQUEUE flag during device close, allowing command timeouts to be queued while the hdev workqueue is being drained on the reset path. The fix, present in stable trees (6.12.93, 6.18.35, 7.0.12, 7.1), closes a race that a Bluetooth-adjacent attacker could trigger during controller reset. There is no public exploit identified at time of analysis, EPSS risk is low (0.20%), and it is not listed in CISA KEV.

RemediationAI

Vendor-released patch: update to a fixed stable kernel - 6.12.93, 6.18.35, 7.0.12, or 7.1, or backport the fix commits (9cebe4680bb9a72f80c6541eb24af06db7a1fbc9, 47330cc875b36a1cf7b3543cb2cf90a7c603ce0e, 60bceb9a4c693e68cc90ba4b2dfb9e000e8638ff, 525daaea459fc215f432de1b8debbd9144bf97b0) from git.kernel.org/stable. Apply the distribution kernel update matching your branch and reboot. As a compensating control until patched, disable or unload the Bluetooth stack on systems that do not require it (e.g. 'rmmod btusb bluetooth' / blacklist the modules, or 'rfkill block bluetooth'), which removes the attack surface entirely at the cost of losing Bluetooth functionality; where Bluetooth is required, restrict physical/RF proximity and disable the radio when not in use, since the vector is adjacent rather than network-wide. Reference advisory and commits: https://nvd.nist.gov/vuln/detail/CVE-2026-63974.

Affected VersionsENISA

Linux 877afadad2dce8aae1f2aad8ce47e072d4f6165e <47330cc875b36a1cf7b3543cb2cf90a7c603ce0e

Linux 4bf367fa1fefabdf14938d0ac9ed60020389112e

Linux 877afadad2dce8aae1f2aad8ce47e072d4f6165e <525daaea459fc215f432de1b8debbd9144bf97b0

Linux patch: 6.12.93

Linux 877afadad2dce8aae1f2aad8ce47e072d4f6165e <60bceb9a4c693e68cc90ba4b2dfb9e000e8638ff

Linux 6.0

Linux 877afadad2dce8aae1f2aad8ce47e072d4f6165e <9cebe4680bb9a72f80c6541eb24af06db7a1fbc9

Linux patch: 6.18.35

Linux 5.19.2 <5.20

Linux 3b382555706558f5c0587862b6dc03e96a252bba

Linux patch: 7.1

Linux 5.18.18 <5.19

Linux patch: 7.0.12

Linux patch: 0

Affected Packages

euvd linux fix: 5.19, 5.20

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The affected component is the Linux kernel Bluetooth Host Controller Interface synchronization layer (net/bluetooth/hci_sync.c). HCI commands are dispatched through a per-device (hdev) workqueue, and each command arms a timeout work item. When a device is closed via hci_dev_close_sync() - a code path that can now be reached during controller reset - the workqueue is drained. Without the HCI_CMD_DRAIN_WORKQUEUE flag being set, new command-timeout work could still be enqueued onto a workqueue that is mid-drain, creating a race window between teardown and pending work. This is a classic concurrency/lifetime hazard (use-after-free / race-during-teardown class); note the input reports CWE as N/A, so the exact weakness class is not authoritatively assigned. CPE data identifies the vendor/product only generically as cpe:2.3:a:linux:linux:*, with the specific subsystem being Bluetooth.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Sources disagree (Low–High)

Vendor (Linux) PRIMARY 8.8 HIGH

AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

vuln.today AI 5.3 MEDIUM

Bluetooth-adjacent (AV:A); a timing-dependent teardown race justifies AC:H; described impact is teardown instability/DoS (A:H) with no evidenced confidentiality or integrity effect, so C:N/I:N pending CWE confirmation.

3.1 AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

4.0 AV:A/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

SUSE HIGH

Red Hat 5.5 LOW

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorVendor: Linux

Attack Vector

Adjacent

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

CVSS changed

Jul 20, 2026 - 15:22 NVD

8.8 (HIGH)

Patch available

Jul 19, 2026 - 17:19 EUVD

CVE Published

Jul 19, 2026 - 14:55 cve.org

UNKNOWN (no severity yet)

CVE Published

Jul 19, 2026 - 14:55 cve.org

HIGH 8.8

DescriptionCVE.org

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: hci_sync: Set HCI_CMD_DRAIN_WORKQUEUE during device close

Since hci_dev_close_sync() can now be called during the reset path, we should also set HCI_CMD_DRAIN_WORKQUEUE. This avoids queuing timeouts while the hdev workqueue is being drained.

Executive ViewAI

Why It Matters

A kernel vulnerability in the Linux Bluetooth stack (CVE-2026-63974, CVSS 8.8) could allow local attackers to disrupt Bluetooth services or corrupt memory on affected systems; however, no public exploit has been identified at this time. Organizations operating Linux systems with Bluetooth functionality should prioritize patching to address this technically significant threat before exploit methods become publicly available. Patches are currently available across multiple stable kernel branches.

Business Impact: High

Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score

0.2%

Top 90% exploitable

Prevalence

Ubiquitous

Linux kernel Bluetooth stack ships on vast numbers of devices

Data Quality

6 sources

Confidence: High

EUVD

NVD

CVE.org

EPSS MSRC Vendor

VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC No

EPSS 0.2%

Patch available Yes

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

None

System Exposure· derived

Controlled

Automatable· derived

Human Impact

High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +44

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Denial of Service MEDIUM

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

Same weakness CWE-400 – Uncontrolled Resource Consumption

View all

CVE-2023-44487 HIGH POC

7.5

CVE-2021-21341 HIGH POC

7.5

CVE-2022-29885 HIGH POC

7.5

CVE-2026-45498 HIGH POC

7.5

CVE-2016-8610 HIGH

7.5

CVE-2026-28318 HIGH POC

7.5

CVE-2023-38180 HIGH

7.5

CVE-2025-26673 HIGH

7.5

Same technique Denial Of Service

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CVE-2015-5119 CRITICAL POC

9.8

CVE-2011-2462 CRITICAL POC

9.8

CVE-2011-0611 HIGH POC

8.8

CVE-2012-1889 HIGH POC

8.8

CVE-2012-0507 CRITICAL POC

9.8

CVE-2014-1761 HIGH POC

7.8

CVE-2015-5122 CRITICAL POC

9.8

CVE-2011-0609 HIGH POC

7.8

Vendor StatusVendor

SUSE

Severity: Important

Product	Status
SUSE Linux Enterprise Desktop 15 SP7	Affected
SUSE Linux Enterprise Desktop 15 SP7	Affected
SUSE Linux Enterprise High Availability Extension 15 SP7	Affected
SUSE Linux Enterprise High Availability Extension 15 SP7	Affected
SUSE Linux Enterprise High Availability Extension 16.0	Affected

References

Advisories & patches

ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-63974 ADVISORY https://seclists.org/oss-sec/2026/q3/230 ADVISORY https://ubuntu.com/security/notices/USN-8593-1 ADVISORY https://vuldb.com/vuln/380427 REF https://git.kernel.org/stable/c/47330cc875b36a1cf7b3543cb2cf90a7c603ce0e REF https://git.kernel.org/stable/c/525daaea459fc215f432de1b8debbd9144bf97b0 REF https://git.kernel.org/stable/c/60bceb9a4c693e68cc90ba4b2dfb9e000e8638ff REF https://git.kernel.org/stable/c/7b81c1378b79c3143ca3fdb3d18ac0f01cbabb21 REF https://git.kernel.org/stable/c/9cebe4680bb9a72f80c6541eb24af06db7a1fbc9 REF https://git.kernel.org/stable/c/ccf07dfb9d7d1e2c7a1eeb782f90d9b614ebba9c

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