CVE-2026-63948: Bluetooth: L2CAP: fix chan ref leak in l2cap_chan_timeout() on !conn

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-19 · updated 2026-10-30

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.

Affected products

Linux kernel: from 4.19.314 before 4.20; from 5.4.276 before 5.5; from 5.10.217 before 5.10.259; from 5.15.159 before 5.15.210; from 6.1.91 before 6.1.176; from 6.6.31 before 6.6.143 — fixed in 4.20, 5.5, 5.10.259, 5.15.210, 6.1.176, 6.6.143
Linux kernel: from 5.10.217 before 5.10.259; from 5.15.159 before 5.15.210; from 6.1.91 before 6.1.176; from 6.6.31 before 6.6.143; from 4.19.314 before 4.20; from 5.4.276 before 5.5 — fixed in 4.20, 5.10.259, 5.15.210, 5.5, 6.1.176, 6.6.143

How to fix

Upgrade to a fixed version: Linux kernel 4.20, 5.5, 5.10.259, 5.15.210; Linux kernel 4.20, 5.10.259, 5.15.210, 5.5. Check the vendor advisory for mitigations.

References

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