CVE-2026-98108

Bluetooth: L2CAP: fix chan mode for LE_CONN_REQ + EXT_FLOWCTL pchan

State: Published
Severity: 7.5 High
Published: Sep 25, 2026
Updated: Oct 19, 2026
Reserved: Sep 25, 2026

Description

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: L2CAP: fix chan mode for LE_CONN_REQ + EXT_FLOWCTL pchan

l2cap_new_connection() sets default value of channel mode to match the parent channel. l2cap_le_connect_req() left this at the default, and created L2CAP_MODE_EXT_FLOWCTL channels if listening pchan has that mode. This causes FLAG_DEFER_SETUP channels to reply to L2CAP_LE_CONN_REQ with L2CAP_ECRED_CONN_RSP, which is incorrect.

It can also result to stack OOB write (of l2cap_alloc_cid determined values) in l2cap_ecred_rsp_defer(), as l2cap_le_connect_req() does not limit maximum number of deferred channels or check for duplicate ident.

Fix by setting chan->mode correctly in l2cap_le_connect_req().

Also check channel mode in l2cap_ecred_rsp_defer(), and do WARN_ON_ONCE instead of OOB write to make it less brittle.

Scores

CVSS	Score	Vector	Source
3.1	7.5 High	CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	15f02b91056253e8cdc592888f431da0731337b8 to before ad0f44a3f1f688558ed876a0702bc2c82b0df689Affected 15f02b91056253e8cdc592888f431da0731337b8 to before 564ae0e05e598aa895b9dbd18cb7d6eb64752869Affected 15f02b91056253e8cdc592888f431da0731337b8 to before aab17938998b29e75c3324763411aef3e300fc67Affected 15f02b91056253e8cdc592888f431da0731337b8 to before 0e1fc7cab95ad958e55d70a5dfaaea687c9c639fAffected 15f02b91056253e8cdc592888f431da0731337b8 to before 1074bcc57f741223f9fa82ce6afe5c3d783e4d10Affected 15f02b91056253e8cdc592888f431da0731337b8 to before 5d5a625cbc854d4c4f68e4b16fcf6e682d9a9ed1Affected 15f02b91056253e8cdc592888f431da0731337b8 to before 6cb79e6499228cfdbd4b3301371ce74d01cd2f80Affected 15f02b91056253e8cdc592888f431da0731337b8 to before 4ef05db5b08b176a551b4a6287372045998806b0Affected
LinuxLinux	5.7Affected before 5.7Not affected 5.10.271 through 5.10.Not affected 5.15.222 through 5.15.Not affected 6.1.189 through 6.1.Not affected 6.6.158 through 6.6.Not affected 6.12.111 through 6.12.Not affected 6.18.53 through 6.18.Not affected 7.2.7 through 7.2.*Not affected 7.3 and laterNot affected

Product

Versions

LinuxLinux

15f02b91056253e8cdc592888f431da0731337b8 to before ad0f44a3f1f688558ed876a0702bc2c82b0df689Affected
15f02b91056253e8cdc592888f431da0731337b8 to before 564ae0e05e598aa895b9dbd18cb7d6eb64752869Affected
15f02b91056253e8cdc592888f431da0731337b8 to before aab17938998b29e75c3324763411aef3e300fc67Affected
15f02b91056253e8cdc592888f431da0731337b8 to before 0e1fc7cab95ad958e55d70a5dfaaea687c9c639fAffected
15f02b91056253e8cdc592888f431da0731337b8 to before 1074bcc57f741223f9fa82ce6afe5c3d783e4d10Affected
15f02b91056253e8cdc592888f431da0731337b8 to before 5d5a625cbc854d4c4f68e4b16fcf6e682d9a9ed1Affected
15f02b91056253e8cdc592888f431da0731337b8 to before 6cb79e6499228cfdbd4b3301371ce74d01cd2f80Affected
15f02b91056253e8cdc592888f431da0731337b8 to before 4ef05db5b08b176a551b4a6287372045998806b0Affected

LinuxLinux

5.7Affected
before 5.7Not affected
5.10.271 through 5.10.*Not affected
5.15.222 through 5.15.*Not affected
6.1.189 through 6.1.*Not affected
6.6.158 through 6.6.*Not affected
6.12.111 through 6.12.*Not affected
6.18.53 through 6.18.*Not affected
7.2.7 through 7.2.*Not affected
7.3 and laterNot affected

References

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