Bug 2540553 (CVE-2026-97408)

Summary: CVE-2026-97408 kernel: Bluetooth: L2CAP: validate connectionless PSM length
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Bluetooth subsystem. The Logical Link Control and Adaptation Protocol (L2CAP) implementation fails to properly validate the payload length of connectionless frames before reading the Protocol/Service Multiplexer (PSM) field. An adjacent attacker within Bluetooth range can exploit this flaw by transmitting a malformed packet with a truncated payload, causing the parser to read beyond the intended buffer. This out-of-bounds read may result in a system crash leading to a Denial of Service (DoS) or the potential disclosure of kernel memory.
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Description OSIDB Bzimport 2026-09-24 17:13:46 UTC 
In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: L2CAP: validate connectionless PSM length

Connectionless L2CAP frames carry a two-byte PSM at the start of the
payload.  l2cap_recv_frame() currently reads that PSM unconditionally
after validating only the outer L2CAP length.

A malformed connectionless frame with a zero- or one-byte payload can
therefore make the parser read beyond the advertised skb payload and use
tailroom bytes as part of the PSM.  A VHCI-backed QEMU reproducer
injected a one-byte connectionless payload and reached the unchecked
read.

Reject connectionless frames that cannot contain the PSM before reading
or pulling it.  This preserves all valid connectionless frames while
dropping only structurally incomplete packets.
Comment 1 Mauro Matteo Cascella 2026-09-29 09:31:19 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-97408.mbox