# CVE-2026-15460: Missing channel-state validation in Zephyr Bluetooth Classic L2CAP receive path

Status: published. Published: 2026-09-09. Updated: 2026-11-04.

The Bluetooth Classic (BR/EDR) L2CAP receive handler bt_l2cap_br_recv() in subsys/bluetooth/host/classic/l2cap_br.c dispatched inbound data PDUs based only on the destination channel ID, without checking that the target channel had reached the BT_L2CAP_CONNECTED state. A dynamic channel is assigned its RX CID and added to the connection's channel list while still in BT_L2CAP_CONNECTING (and later BT_L2CAP_CONFIG) — before configuration completes and, for PSMs that require security, before the peer is authenticated (l2cap_br_conn_req()).

Because the channel is already findable by bt_l2cap_br_lookup_rx_cid() during this window, a remote peer within radio range can send a data PDU addressed to that CID and have it processed on a not-yet-established channel. The dispatch keys off channel fields (BR_CHAN(chan)->rx.mode, rx.mps) that are only initialized during configuration by l2cap_br_conf(); since channel objects are pooled and bt_l2cap_br_chan_del() does not reset rx.mode or the reassembly buffer _sdu, a reused channel can carry stale state into the CONNECTING window and route the frame into the retransmission/flow-control path (bt_l2cap_br_ret_fc_recv()) with stale parameters and a possibly stale _sdu pointer.

The impact is delivery of attacker data to upper-layer protocol handlers on a half-open (and possibly unauthenticated) channel, plus operation on stale or partially initialized channel state on reused channel objects — leading to channel/link teardown (denial of service) and, in the stale-_sdu case, a dangling-pointer condition. The fix adds an explicit BR_CHAN(chan)->state < BT_L2CAP_CONNECTED guard that drops any data received before the channel is fully connected.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: zephyr) — https://github.com/zephyrproject-rtos/zephyr/commit/2738ee921ba61ba2e644c95bceba302896dd8c19

## Affected products and versions

- zephyrproject / zephyr (zephyr): ≥ 1.6.0; < 4.3.2 (affected, semver); ≥ 4.4.0; < 4.4.2 (affected, semver). Source: CNA: zephyr

## Severity and prioritization

- CVSS 3.1: 5.4 (medium); CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L; source: CNA: zephyr

- CVSS 3.1: 5.4 (medium); CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L; source: NVD: vulnerabilities@zephyrproject.org

- CISA KEV: No listing in collected sources

- EPSS: 0.25% as of 2026-11-03; percentile 16.33%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-666

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/zephyrproject-rtos/zephyr/commit/2738ee921ba61ba2e644c95bceba302896dd8c19 (CNA: zephyr; patch)

- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-hx89-rm6c-hjrh (CNA: zephyr)

- https://github.com/zephyrproject-rtos/zephyr/commit/2738ee921ba61ba2e644c95bceba302896dd8c19 (vulnerabilities@zephyrproject.org)

- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-hx89-rm6c-hjrh (vulnerabilities@zephyrproject.org)

## Provenance

- CNA: zephyr: https://www.cve.org/CVERecord?id=CVE-2026-15460; retrieved 2026-11-04; source updated 2026-11-04

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-15460; retrieved 2026-11-04; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-15460; retrieved 2026-11-04; source updated Not reported

Revision: b6436d03196d3cb31337ae9885133dc9ec0d32a082008c4e8d7383664df88179

Canonical: https://y2.dev/cve/CVE-2026-15460

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