Medium [CVE-2026-68339] Linux kernel: Bluetooth subsystem denial of service via improper Realtek vendor event length validation
This medium-severity Red Hat Linux advisory covers CVE-2026-68339.
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Summary
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: btusb: validate Realtek vendor event length btusb_recv_event_realtek() reads the event code at data[0] and the Realtek subevent code at data[2] before deciding whether to consume a vendor event as a coredump.
For example, the two-byte event ff 00 contains a complete vendor-event header declaring zero parameters. The old classifier still reads a nonexistent third byte and can misclassify the event as a coredump if the adjacent byte is 0x34.
Require the HCI event header and first parameter to be present before inspecting the Realtek subevent code. Short events continue through the normal HCI receive path, which owns their protocol validation.
An attacker could craft a two-byte vendor event that, due to improper validation of the Realtek vendor event length in the `btusb_recv_event_realtek()` function, could lead to the system attempting to read a non-existent third byte. This misclassification of the event as a coredump could result in a denial of service (DoS).
Red Hat severity: Moderate — CVSS 6.5 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-125.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 1 hour ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 1 hour ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 1 hour ago·verify at source
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