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CVE-2026-19741

OpenThread joiner autostart uses a publicly documented default Joining Device Credential (PSKd)

Products / packages zephyrproject zephyr

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Severity and exploitation

Not in CISA KEV

KEV coverage does not rule out exploitation.

KEV checked 15/11/2026, 00:30:33 UTC
zephyr · CVSS:3.1 · 7.5
Assessment vectorCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Severity

high7.5

CVSS measures technical severity, not the likelihood of an attack.

Known exploitation

Not listed in the checked CISA KEV catalog

Absence from CISA KEV does not rule out attacks.

Public exploit

Not established by this record

Missing evidence does not mean no public exploit exists.

Remediation

Fix status not established

No structured fix or guidance is available here. Check the latest publisher advisory.

What this means

Zephyr's OpenThread integration defined CONFIG_OPENTHREAD_JOINER_PSKD 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/echo_client/README.rst, so it is not a secret. A firmware image built with CONFIG_OPENTHREAD_JOINER_AUTOSTART=y that never overrode the PSKd therefore shipped with a publicly known joining credential…

Source excerpt · zephyr

Attack conditions

No attack-condition excerpt has been identified here. Review the full source description and references for authentication, network access, and configuration requirements.

Review supporting sources →

Affected versions

Check the exact model, release, and any platform requirements against your installation.

zephyrproject · zephyr

zephyr

2 ranges
zephyr version evidence

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affected

1.14.0 → before 4.3.2

semver versions

4.4.0 → before 4.5.0

semver versions

unaffected

unknown

Other versions: unaffected

Automatic dependency matching is unavailable for this record. Use the product evidence and publisher’s instructions to check your installation.

What to do

Compare your installed product and version with the affected versions above. A matching product name alone does not confirm exposure.

No structured fix or remediation guidance is available here. Check the full source description and vendor’s latest advisory for a patch or workaround; do not assume another version is safe.

cve.new guidance unless attributed to a publisher. This page does not inspect your installation.

Public exploit evidence

No public exploit reference is identified in the imported evidence. This is not a claim that no exploit exists.

Original source description

Read the full publisher description

Zephyr's OpenThread integration defined CONFIG_OPENTHREAD_JOINER_PSKD 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/echo_client/README.rst, so it is not a secret. A firmware image built with CONFIG_OPENTHREAD_JOINER_AUTOSTART=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 ot_configure_instance() (modules/openthread/openthread.c), a device with no stored dataset calls otJoinerStart() with the configured PSKd, and ot_joiner_start_handler() 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 any stock Thread commissioner registered with J01NME, complete the handshake, and hand the device an attacker-controlled operational dataset.

The device then joins and enables Thread on the attacker's mesh. The attacker becomes its router, seeing, dropping, injecting and spoofing all of the device's IPv6 traffic and impersonating the peers the application expects, while the device is cut off from the network it was meant to join and stays mis-provisioned until it is reset. Only application-layer security with independently provisioned credentials survives. Exposure is limited to builds that enable joiner autostart and leave the PSKd unset; the option is not enabled by default and no in-tree sample uses the vulnerable combination.

The fix removes the default from CONFIG_OPENTHREAD_JOINER_PSKD and adds a BUILD_ASSERT() in modules/openthread/openthread.c, active only under CONFIG_OPENTHREAD_JOINER_AUTOSTART, that fails the build unless a 6-to-32-character PSKd is configured. Products should provision a per-device PSKd from factory data and call otJoinerStart() from the application rather than relying on a credential compiled identically into every unit.

References

2 sources
zephyrproject-rtos/zephyr · commit acb3e51
Patchzephyr
zephyrproject-rtos/zephyr · security/advisories/GHSA-6j2r-xrm4-3v7f
Security advisoryzephyr

Inside the record

Evidence available

Package identity · not supplied
Version evidence
Remediation guidance · not supplied
Weakness classification
Additional publishers

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-19741

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Underlying weaknesses

The source’s classification of what caused the vulnerability.

CWE-1392 ↗

auth

zephyr

Related →
Contributing organizations · 2
zephyr

Assigning organization

2026-11-04
CISA-ADP

Additional data publisher

2026-11-02

Timeline

All times UTC

  1. Advisory published

    Publication date supplied by the source.

  2. Source updated

    Latest modification date supplied by the source.

  3. Last imported by cve.new

    Latest catalog import, not the date we first saw this advisory.

What changed

Follow changes
  1. CVE · CVE-2026-19741

    Observed 2026-11-04T05:16:15.300Z · upstream updated 2026-11-04T05:01:23.860Z

    Product or version evidence changed

    before

    [
  {
    "vendor": "zephyrproject",
    "name": "zephyr",
    "platforms": [],
    "versions": [
      {
        "version": "1.14.0",
        "status": "affected",
        "lessThan": "4.5.0",
        "versionType": "semver"
      }
    ],
    "defaultStatus": "unaffected",
    "cpes": [],
    "source": "zephyr",
    "url": "https://www.cve.org/CVERecord?id=CVE-2026-19741"
  }
]

    after

    [
  {
    "vendor": "zephyrproject",
    "name": "zephyr",
    "platforms": [],
    "versions": [
      {
        "version": "1.14.0",
        "status": "affected",
        "lessThan": "4.3.2",
        "versionType": "semver"
      },
      {
        "version": "4.4.0",
        "status": "affected",
        "lessThan": "4.5.0",
        "versionType": "semver"
      }
    ],
    "defaultStatus": "unaffected",
    "cpes": [],
    "source": "zephyr",
    "url": "https://www.cve.org/CVERecord?id=CVE-2026-19741"
  }
]

Large field values are marked as truncated previews. Original source snapshots remain retained.

Showing up to 50 most recent observed changes.