Bug 2492795 (CVE-2026-53254)

Summary: CVE-2026-53254 kernel: Bluetooth: RFCOMM: validate skb length in MCC handlers
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Bluetooth RFCOMM (Radio Frequency Communication) subsystem. A malicious remote device could exploit this vulnerability by sending specially crafted, truncated Multiplexing Control Channel (MCC) frames. This lack of proper validation of incoming data length before processing could lead to out-of-bounds reads, potentially resulting in information disclosure or a denial of service.
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Description OSIDB Bzimport 2026-06-25 10:06:10 UTC 
In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: RFCOMM: validate skb length in MCC handlers

The RFCOMM MCC handlers cast skb->data to protocol-specific structs
without validating skb->len first. A malicious remote device can send
truncated MCC frames and trigger out-of-bounds reads in these handlers.

Fix this by using skb_pull_data() to validate and access the required
data before dereferencing it.

rfcomm_recv_rpn() requires special handling since ETSI TS 07.10 allows
1-byte RPN requests. Handle this by validating only the DLCI byte first,
and validating the full struct only when len > 1.
Comment 1 Keith Grant 2026-06-26 00:28:47 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062514-CVE-2026-53254-82af@gregkh/T