What’s Vulnerable › Vulnerabilities

CVE-2023-53297: Bluetooth: L2CAP: fix "bad unlock balance" in l2cap_disconnect_rsp

• 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: 2025-09-16 · updated 2026-08-04

Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: fix "bad unlock balance" in l2cap_disconnect_rsp conn->chan_lock isn't acquired before l2cap_get_chan_by_scid, if l2cap_get_chan_by_scid returns NULL, then 'bad unlock balance' is triggered.

Affected products

• Linux kernel: before 4.14.316; from 4.15 before 4.19.284; from 4.20 before 5.4.244; from 5.5 before 5.10.181; from 5.11 before 5.15.113; from 5.16 before 6.1.30 — fixed in 4.14.316, 4.19.284, 5.10.181, 5.15.113, 5.4.244, 6.1.30

How to fix

Upgrade to a fixed version: Linux kernel 4.14.316, 4.19.284, 5.10.181, 5.15.113. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/116b9c002c894097adc2b8684db2d1da4229ed46
• https://git.kernel.org/stable/c/2112c4c47d36bc5aba3ddeb9afedce6ae6a67e7d
• https://git.kernel.org/stable/c/25e97f7b1866e6b8503be349eeea44bb52d661ce
• https://git.kernel.org/stable/c/5134556c9be582793f30695c09d18a26fe1ff2d7
• https://git.kernel.org/stable/c/55410a9144c76ecda126e6cdec556dfcd8f343b2
• https://git.kernel.org/stable/c/5f352a56f0e607e6ff539cbf12156bfd8af232be
• https://git.kernel.org/stable/c/6a27762340ad08643de3bc17fe1646ea489ca2e2
• https://git.kernel.org/stable/c/fd269a0435f8e9943b7a57c5a59688848d42d449

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