UBUNTU-CVE-2026-19741

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Source
https://ubuntu.com/security/CVE-2026-19741
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19741.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-19741
Upstream
Published
2026-10-23T20:17:00Z
Modified
2026-10-28T17:32:48Z
Severity
  • 7.5 (High) CVSS_V3 - CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

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

Affected packages

Ubuntu:16.04:LTS
zephyr

Package

Name
zephyr
Purl
pkg:deb/ubuntu/zephyr?arch=source&distro=xenial

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

3.*
3.1.2-1
3.1.2-1build1

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "libzephyr4",
            "binary_version":  "3.1.2-1build1"
        },
        {
            "binary_name":  "libzephyr4-krb5",
            "binary_version":  "3.1.2-1build1"
        },
        {
            "binary_name":  "zephyr-clients",
            "binary_version":  "3.1.2-1build1"
        },
        {
            "binary_name":  "zephyr-server",
            "binary_version":  "3.1.2-1build1"
        },
        {
            "binary_name":  "zephyr-server-krb5",
            "binary_version":  "3.1.2-1build1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19741.json"
Ubuntu:18.04:LTS
zephyr

Package

Name
zephyr
Purl
pkg:deb/ubuntu/zephyr?arch=source&distro=bionic

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

3.*
3.1.2-1build1
3.1.2-1build2

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "libzephyr4",
            "binary_version":  "3.1.2-1build2"
        },
        {
            "binary_name":  "libzephyr4-krb5",
            "binary_version":  "3.1.2-1build2"
        },
        {
            "binary_name":  "zephyr-clients",
            "binary_version":  "3.1.2-1build2"
        },
        {
            "binary_name":  "zephyr-server",
            "binary_version":  "3.1.2-1build2"
        },
        {
            "binary_name":  "zephyr-server-krb5",
            "binary_version":  "3.1.2-1build2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19741.json"
Ubuntu:20.04:LTS
zephyr

Package

Name
zephyr
Purl
pkg:deb/ubuntu/zephyr?arch=source&distro=focal

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

3.*
3.1.2-1build3

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "libzephyr4",
            "binary_version":  "3.1.2-1build3"
        },
        {
            "binary_name":  "libzephyr4-krb5",
            "binary_version":  "3.1.2-1build3"
        },
        {
            "binary_name":  "zephyr-clients",
            "binary_version":  "3.1.2-1build3"
        },
        {
            "binary_name":  "zephyr-server",
            "binary_version":  "3.1.2-1build3"
        },
        {
            "binary_name":  "zephyr-server-krb5",
            "binary_version":  "3.1.2-1build3"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19741.json"
Ubuntu:22.04:LTS
zephyr

Package

Name
zephyr
Purl
pkg:deb/ubuntu/zephyr?arch=source&distro=jammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

3.*
3.1.2-1build3

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "libzephyr4",
            "binary_version":  "3.1.2-1build3"
        },
        {
            "binary_name":  "libzephyr4-krb5",
            "binary_version":  "3.1.2-1build3"
        },
        {
            "binary_name":  "zephyr-clients",
            "binary_version":  "3.1.2-1build3"
        },
        {
            "binary_name":  "zephyr-server",
            "binary_version":  "3.1.2-1build3"
        },
        {
            "binary_name":  "zephyr-server-krb5",
            "binary_version":  "3.1.2-1build3"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19741.json"
Ubuntu:24.04:LTS
zephyr

Package

Name
zephyr
Purl
pkg:deb/ubuntu/zephyr?arch=source&distro=noble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

3.*
3.1.2-1.1
3.1.2-1.1build1

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "libzephyr4",
            "binary_version":  "3.1.2-1.1build1"
        },
        {
            "binary_name":  "libzephyr4-krb5",
            "binary_version":  "3.1.2-1.1build1"
        },
        {
            "binary_name":  "zephyr-clients",
            "binary_version":  "3.1.2-1.1build1"
        },
        {
            "binary_name":  "zephyr-server",
            "binary_version":  "3.1.2-1.1build1"
        },
        {
            "binary_name":  "zephyr-server-krb5",
            "binary_version":  "3.1.2-1.1build1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19741.json"
Ubuntu:26.04:LTS
zephyr

Package

Name
zephyr
Purl
pkg:deb/ubuntu/zephyr?arch=source&distro=resolute

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

3.*
3.1.2-1.1build1
3.1.2-4

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "libzephyr4",
            "binary_version":  "3.1.2-4"
        },
        {
            "binary_name":  "libzephyr4-krb5",
            "binary_version":  "3.1.2-4"
        },
        {
            "binary_name":  "zephyr-clients",
            "binary_version":  "3.1.2-4"
        },
        {
            "binary_name":  "zephyr-server",
            "binary_version":  "3.1.2-4"
        },
        {
            "binary_name":  "zephyr-server-krb5",
            "binary_version":  "3.1.2-4"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19741.json"
Ubuntu:26.10
zephyr

Package

Name
zephyr
Purl
pkg:deb/ubuntu/zephyr?arch=source&distro=stonking

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

3.*
3.1.2-4

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "libzephyr4",
            "binary_version":  "3.1.2-4"
        },
        {
            "binary_name":  "libzephyr4-krb5",
            "binary_version":  "3.1.2-4"
        },
        {
            "binary_name":  "zephyr-clients",
            "binary_version":  "3.1.2-4"
        },
        {
            "binary_name":  "zephyr-server",
            "binary_version":  "3.1.2-4"
        },
        {
            "binary_name":  "zephyr-server-krb5",
            "binary_version":  "3.1.2-4"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19741.json"