CVE-2026-63948 Bluetooth: L2CAP: fix chan ref leak in l2cap_chan_timeout() on !conn
A reference leak in the Linux kernel Bluetooth L2CAP module can lead to memory exhaustion and denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-63948?
CVE-2026-63948 is a memory corruption vulnerability in Linux, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: L2CAP: fix chan ref leak in l2cap_chan_timeout() on !conn
__set_chan_timer() takes a l2cap_chan reference via l2cap_chan_hold() before scheduling the delayed work. The normal path in l2cap_chan_timeout() drops this reference with l2cap_chan_put() at the end, but the early return when chan->conn is NULL skips the put, leaking the reference.
Add the missing l2cap_chan_put() before the early return.
Which versions are affected by CVE-2026-63948?
How do I fix CVE-2026-63948?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-63948 being exploited?
There is no known exploitation of CVE-2026-63948 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-63948, DEBIAN-CVE-2026-63948, GHSA-jg7r-p8w6-9pmq, ROOT-OS-UBUNTU-2204-CVE-2026-63948, UBUNTU-CVE-2026-63948.