CVE-2025-62235: 
NixOS vulnerability analysis and mitigation

CVE-2025-62235 is an Authentication Bypass by Spoofing vulnerability (CWE-290) in Apache NimBLE, an open-source Bluetooth Low Energy (BLE) stack used in embedded and IoT devices. A specially crafted BLE Security Manager Protocol (SMP) Security Request can cause a vulnerable device to remove its existing bond and re-pair with an impostor device. All versions of Apache NimBLE through 1.8.0 are affected; version 1.9.0 resolves the issue. The vulnerability was disclosed on January 10, 2026, and carries a CVSS v3.1 base score of 8.1 (High) (Apache Mailing List, Openwall OSS-Sec).

The root cause lies in improper handling of SMP Security Requests in the ble_sm_sec_req_rx() function within nimble/host/src/ble_sm.c. Prior to the fix, the code did not require that the peer be authenticated (i.e., the link be encrypted) before allowing security level elevation or re-bonding; a crafted Security Request could therefore trigger removal of the existing bond and initiation of a new pairing with an unauthenticated device. The patch (commit 41f67e3) adds a check requiring link encryption before processing Security Requests for security elevation, and treats unauthenticated peers as a 'lost bond' scenario rather than a legitimate re-bond request. The attack vector is adjacent network (Bluetooth range), requires no privileges or user interaction, and has low attack complexity (GitHub Patch, Openwall OSS-Sec).

Successful exploitation allows an attacker within Bluetooth range to impersonate a previously bonded device, causing the victim device to drop its legitimate bond and establish a new pairing with the attacker-controlled impostor. This results in high confidentiality impact (interception of encrypted BLE communications) and high integrity impact (unauthorized control or data injection into the paired device relationship), with no direct availability impact. IoT and smart home devices running Apache NimBLE are particularly at risk, as compromised bonds can enable persistent unauthorized access and communication interception (Openwall OSS-Sec, Apache Mailing List).

1. Reconnaissance: Identify target devices running Apache NimBLE (versions ≤ 1.8.0) within Bluetooth range using BLE scanning tools such as btlejuice, bettercap, or nRF Sniffer. Look for devices advertising BLE services that indicate use of the NimBLE stack.
2. Observe existing bond: Monitor BLE traffic to confirm the target device has an established bond with a legitimate central device.
3. Craft malicious Security Request: Construct a specially crafted SMP Security Request packet. The request exploits the lack of authentication enforcement in the ble_sm_sec_req_rx() handler, which previously did not verify that the link was already encrypted before processing the request.
4. Transmit the crafted packet: Send the malicious Security Request to the target peripheral device while acting as a central (or spoofing a central role), triggering the vulnerable code path.
5. Force bond removal and re-pairing: The vulnerable device removes its existing bond with the legitimate device and initiates a new pairing procedure with the attacker's device.
6. Establish impostor bond: Complete the pairing process with the victim device, gaining an authenticated bond that allows interception of encrypted communications and unauthorized control of the device (Openwall OSS-Sec, GitHub Patch).

• Network/Bluetooth: Unexpected BLE pairing or bonding events from unknown or new device addresses; SMP Security Request packets received from devices not previously bonded; sudden loss of existing bond followed by a new pairing event.
• Device Behavior: Devices unexpectedly entering pairing mode or displaying pairing prompts without user initiation; loss of connectivity with previously paired legitimate devices.
• Logs: BLE host stack logs showing bond deletion events (ble_store key removal) followed immediately by new pairing initiation (ble_sm_pair_initiate) from a different peer address; log entries indicating 'lost bond' scenario triggered by an incoming Security Request.
• Process/State: Unexpected changes in the bonded device list stored in non-volatile memory; new bond entries for unrecognized Bluetooth device addresses.

The primary remediation is to upgrade Apache NimBLE to version 1.9.0 or later, which includes the fix in commit 41f67e3 that enforces peer authentication before allowing security level elevation via Security Requests (GitHub Patch, Apache Mailing List). No official configuration-based workaround has been published; upgrading is the recommended and only confirmed fix. Organizations using embedded devices or IoT products built on Apache NimBLE should audit their firmware versions and prioritize patching, particularly for devices deployed in sensitive or publicly accessible environments (Openwall OSS-Sec).

The vulnerability received coverage from security news outlets including SecurityOnline.info, which highlighted the Bluetooth spoofing and eavesdropping risks (SecurityOnline). Social media discussion appeared on Bluesky and Mastodon via infosec community accounts, and TheHackerWire covered the CVE. A blog post titled 'Billions of Devices at Risk' on code.blog drew attention to the potential scale of impact given NimBLE's widespread use in IoT and smart home devices (code.blog). Community sentiment emphasized the broad attack surface given NimBLE's deployment across numerous embedded platforms.