7.5 High

Zephyr's OpenThread integration defined CONFIGOPENTHREADJOINERPSKD with default "J01NME" in modules/openthread/Kconfig.thread (previously…

CVE-2026-19741

Zephyr's OpenThread integration defined CONFIGOPENTHREADJOINERPSKD with default "J01NME" in modules/openthread/Kconfig.thread (previously subsys/net/l2/openthread/Kconfig, then subsys/net/l2/openthread/Kconfig.thread). J01NME is the example Joining Device Credential used throughout the public OpenThread and Thread commissioning documentation, including Zephyr's own samples/net/sockets/echoclient/README.rst, so it is not a secret. A firmware image built with CONFIGOPENTHREADJOINERAUTOSTART=y that never overrode the PSKd therefore shipped with a publicly known joining credential compiled in, with no build-time or run-time warning. The PSKd is the only value that authenticates Thread commissioning: joiner and commissioner run a DTLS-PSK handshake keyed on it, after which the commissioner supplies the full operational dataset. In otconfigureinstance() (modules/openthread/openthread.c), a device with no stored dataset calls otJoinerStart() with the configured PSKd, and otjoinerstarthandler() calls otThreadSetEnabled() on success. An unauthenticated attacker within 802.15.4 radio range of an uncommissioned device (factory-fresh, after a factory reset, or after a settings erase) can run…

Assessment

CVSS: 7.5 (v3.1)
Severity: High
EPSS: 0.26% chance of exploitation in the next 30 days
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 23 October 2026
Last updated: 26 October 2026
Affected: zephyrproject
Weakness: CWE-1392
Assigner: vulnerabilities@zephyrproject.org

CVSS vectorCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

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