VulnerabilityPublished 6 Oct 2026Updated 19 Oct 2026

CVE-2026-98294: Linux kernel · Bluetooth: hci_qca: Do not write to the serial port after it is closed

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in a5414b0a9464b863733c8bd97493cb443a210ec4 : patch Linux kernel soon.

Data as of 26 Oct 2026, 13:47 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in a5414b0a9464b863733c8bd97493cb443a210ec4, 15754e4ec47ac5d117c9609c34a49ed6980ac4a1, 4e93c65f87825e1e012bce56615320aeb123815d

Exploitation evidence

Disclosed: evidence found.
CVE published 6 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Linux kernel to a5414b0a9464b863733c8bd97493cb443a210ec4, 15754e4ec47ac5d117c9609c34a49ed6980ac4a1 or 4e93c65f87825e1e012bce56615320aeb123815d.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ fa9ad876b8e0ebd2b4367ef1580f89be64ebd5d3, < a5414b0a9464b863733c8bd97493cb443a210ec4	Fixed in a5414b0a9464b863733c8bd97493cb443a210ec4
LinuxLinux	Affected ≥ fa9ad876b8e0ebd2b4367ef1580f89be64ebd5d3, < 15754e4ec47ac5d117c9609c34a49ed6980ac4a1	Fixed in 15754e4ec47ac5d117c9609c34a49ed6980ac4a1
LinuxLinux	Affected ≥ fa9ad876b8e0ebd2b4367ef1580f89be64ebd5d3, < 4e93c65f87825e1e012bce56615320aeb123815d	Fixed in 4e93c65f87825e1e012bce56615320aeb123815d
LinuxLinux	Affected =4.19	Fixed in–

AI-suggested

A fix is available in the Linux kernel as indicated by the fixed commit versions. Users and administrators should update to a Linux kernel version that includes these commits to remediate the issue. No additional mitigation steps are indicated or required beyond applying the official fix.

Description

A vulnerability in the Linux kernel Bluetooth subsystem (hci_qca driver) allows writing to a serial port after it has been closed, which can lead to a kernel NULL pointer dereference and potential system crash. This occurs due to improper handling of port closure and power state flags in certain Qualcomm Bluetooth controllers such as the WCN399x family. The issue has been fixed in specific Linux kernel commits.

Impact

This vulnerability can cause a kernel NULL pointer dereference leading to a system crash (kernel panic) when the Bluetooth driver attempts to write to a closed serial port. This affects system stability and could potentially be triggered by unbinding the driver after a controller failure. There is no indication of code execution or privilege escalation from the provided data.

Summary

The Linux kernel Bluetooth hci_qca driver had a flaw where hci_uart_close() would close the serdev port under certain conditions but leave power regulators marked as on. Subsequent calls to qca_power_off() would write to the already closed serial port unconditionally, causing a NULL pointer dereference and kernel crash. This was observed on WCN3988 hardware when unbinding the driver after a controller failure. The fix involves checking the HCI_UART_PROTO_READY flag before writing to the port and ensuring proper power down without writing to a closed port. A related use-after-free issue with the dangling serport->tty pointer is addressed separately.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 11:53 UTC

Technical details

References

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