CVE-2026-11893

BLE stack crash via HCI buffer double-unref

Published Aug 11, 2026 · Updated Aug 11, 2026

Double free in Zephyr RTOS 4.4.0 through 4.4.1 allows physically proximate attackers to crash the BLE stack via HCI send errors. The Bouffalo Lab HCI driver's bt_bflb_send() unrefs a failed TX buffer that the host TX path then unrefs again, freeing a queued parent buffer. Reachability requires a BL60x, BL70x, or BL61x on-chip BLE controller and an HCI transmit error, leading to pool corruption and a device crash.

CVSS severity5.9
Medium
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Double free in Zephyr RTOS 4.4.0 through 4.4.1 allows physically proximate attackers to crash the BLE stack via HCI send errors. The Bouffalo Lab HCI driver's bt_bflb_send() unrefs a failed TX buffer that the host TX path then unrefs again, freeing a queued parent buffer. Reachability requires a BL60x, BL70x, or BL61x on-chip BLE controller and an HCI transmit error, leading to pool corruption and a device crash.

The record

CVE
CVE-2026-11893
Published
Aug 11, 2026
Updated
Aug 11, 2026
Vendor
Zephyr Project
Product
Zephyr RTOS
Classifications
CWE-415, T1499.004
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.4.0 <4.4.2

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Zephyr Project · Zephyr RTOSversion=4.4.0 <4.4.2

Published CVSS scores

5.9GitHubCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-415Double Free
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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