CVE-2026-31393 Bluetooth: L2CAP: Validate L2CAP_INFO_RSP payload length before access
A missing length check in the Linux kernel Bluetooth L2CAP handler allows attackers to read out-of-bounds memory via a truncated response.
- 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-2026-31393?
CVE-2026-31393 is a high-severity vulnerability in Linux kernel, published on 3 Apr 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: Validate L2CAP_INFO_RSP payload length before access
l2cap_information_rsp() checks that cmd_len covers the fixed l2cap_info_rsp header (type + result, 4 bytes) but then reads rsp->data without verifying that the payload is present:
- L2CAP_IT_FEAT_MASK calls get_unaligned_le32(rsp->data), which reads 4 bytes past the header (needs cmd_len >= 8).
- L2CAP_IT_FIXED_CHAN reads rsp->data[0], 1 byte past the header (needs cmd_len >= 5).
A truncated L2CAP_INFO_RSP with result == L2CAP_IR_SUCCESS triggers an out-of-bounds read of adjacent skb data.
Guard each data access with the required payload length check. If the payload is too short, skip the read and let the state machine complete with safe defaults (feat_mask and remote_fixed_chan remain zero from kzalloc), so the info timer cleanup and l2cap_conn_start() still run and the connection is not stalled.
Weakness: CWE-125
Which versions are affected by CVE-2026-31393?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31393?
Apply the vendor's patch.
Is CVE-2026-31393 being exploited?
There is no known exploitation of CVE-2026-31393 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-31393, DEBIAN-CVE-2026-31393, GHSA-cpmg-r9cr-q8pj, ROOT-OS-DEBIAN-11-CVE-2026-31393, ROOT-OS-DEBIAN-12-CVE-2026-31393, ROOT-OS-DEBIAN-13-CVE-2026-31393 and 3 more.