Linux Kernel up to 7.0.12 Bluetooth l2cap_core.c l2cap_sig_channel stack-based overflow

Summaryinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 7.0.12. Affected by this issue is the function l2cap_sig_channel of the file net/bluetooth/l2cap_core.c of the component Bluetooth. The manipulation results in stack-based overflow. This vulnerability is cataloged as CVE-2026-53208. The attack must originate from the local network. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.0.12. It has been classified as critical. Affected is the function l2cap_sig_channel of the file net/bluetooth/l2cap_core.c of the component Bluetooth. The manipulation with an unknown input leads to a stack-based overflow vulnerability. CWE is classifying the issue as CWE-121. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function). This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: reject BR/EDR signaling packets over MTUsig net/bluetooth/l2cap_core.c:l2cap_sig_channel() accepts BR/EDR signaling packets up to the channel MTU and dispatches each command without enforcing the signaling MTU (MTUsig). A Bluetooth BR/EDR peer within radio range can send a fixed-channel CID 0x0001 packet that is larger than MTUsig and contains many L2CAP_ECHO_REQ commands before pairing. In a real-radio stock-kernel run, one 681-byte signaling packet containing 168 zero-length ECHO_REQ commands made the target transmit 168 ECHO_RSP frames over about 220 ms. Impact: a Bluetooth BR/EDR peer within radio range, before pairing, can force 168 ECHO_RSP frames from one 681-byte fixed-channel signaling packet containing packed ECHO_REQ commands. Define Linux's BR/EDR signaling MTU as the spec minimum of 48 bytes and reject any larger signaling packet with one L2CAP_COMMAND_REJECT_RSP carrying L2CAP_REJ_MTU_EXCEEDED before any command is dispatched. The Bluetooth Core spec wording for MTUExceeded says the reject identifier shall match the first request command in the packet, and that packets containing only responses shall be silently discarded. Linux intentionally deviates from that prescription: silently discarding desynchronizes the peer because the remote stack never learns its responses were dropped, and locating the first request command requires walking command headers past MTUsig, i.e. processing bytes from a packet we have already decided is too large to process. We therefore always emit one reject and use the identifier from the first command header, a single fixed-offset byte read. The unrestricted BR/EDR signaling parser and ECHO_REQ response path both trace to the initial git import; no later introducing commit is available for a Fixes tag.

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2026-53208 since 06/09/2026. The exploitability is told to be easy. The attack can only be initiated within the local network. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 06/25/2026).

Upgrading to version 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.94, 6.18.36 or 7.0.13 eliminates this vulnerability. Applying the patch e05c4ac575b457978a7ef441053394169084869c/fa5823126239b3e453fac1a2fe50726c7f4a55e1/b20e8a98dd29b121f58fcdf51e8576119aba536a/214a2042b16b3c8d798a8b9ef9f36094f13a9859/a8335f3db15bd1e0e82e0db5d488fabc7d10d1ab/dedc92b96dc1d8919a3bdf2495ede68922ef7ebc/e2b8acf9405bd9b1baf1c54dc897b0905db689bf/dd214733544427587a95f66dbf3adff072568990 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.10.258
• 5.15.209
• 6.1.175
• 6.6.142
• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
• 6.12.4
• 6.12.5
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• 6.12.87
• 6.12.88
• 6.12.89
• 6.12.90
• 6.12.91
• 6.12.92
• 6.12.93
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
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• 6.18.11
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• 6.18.35
• 7.0.0
• 7.0.1
• 7.0.2
• 7.0.3
• 7.0.4
• 7.0.5
• 7.0.6
• 7.0.7
• 7.0.8
• 7.0.9
• 7.0.10
• 7.0.11
• 7.0.12

License

• open-source

Website

• Vendor: https://www.kernel.org/

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