{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2026-19742 in the wild and no public exploit code.","fix":"No fix has been published for CVE-2026-19742 yet. Limit exposure of the affected software until one is available.","what":"CVE-2026-19742 is a low-severity vulnerability in zephyrproject zephyr, published on 26 Oct 2026."},"fix_prompt":"Check this codebase for CVE-2026-19742 and fix it if it is affected.\n\nWhat it is: CVE-2026-19742 is a low-severity vulnerability in zephyrproject zephyr, published on 26 Oct 2026. \nExploitation: There is no known exploitation of CVE-2026-19742 in the wild and no public exploit code.\n\nAffected product: zephyrproject zephyr. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-19742/ (Markdown: https://insights.sbomify.com/CVE-2026-19742/index.md)","id":"CVE-2026-19742","markdown":"https://insights.sbomify.com/CVE-2026-19742/index.md","name":"CVE-2026-19742","record":{"aliases":["GHSA-xfm2-gr93-8mx9","UBUNTU-CVE-2026-19742"],"analysis":null,"analysis_generated_by":null,"assigner":"zephyr","cpe":[],"cvss":{"score":3.7,"severity":"low","source":"cna","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N","version":"3.1"},"cwes":[{"id":"CWE-338","name":"Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)"}],"description":"The IPv6 stack derived the long-lived secret key used to compute RFC 7217 stable interface identifiers (gen_stable_iid() in subsys/net/ip/ipv6.c) and RFC 8981 temporary interface identifiers (gen_temporary_iid() in subsys/net/ip/ipv6_pe.c) with sys_rand_get(). That API is documented as not cryptographically secure, while both RFCs require this key to be an unpredictable random value of at least 128 bits — the unpredictability of every generated IID rests entirely on it.\n\nDepending on the platform, sys_rand_get() resolves either to a hardware entropy device or, on boards whose entropy driver sets CONFIG_ENTROPY_NEEDS_PRNG, to the non-cryptographic xoshiro128++ generator in subsys/random/random_xoshiro128.c, which keeps a single global 128-bit state shared with every other sys_rand_get() consumer. Many of those consumers put their output directly on the wire (ephemeral source ports, DNS query IDs, CoAP message IDs and tokens, DHCPv6 transaction IDs, WebSocket masking keys), and the xoshiro state transition is invertible, so an observer of a device's traffic can recover the generator state and reconstruct the IID secret key. Additionally, with the entropy-device backend sys_rand_get() silently falls back to k_cycle_get_32() samples when the entropy driver fails, and returns no error, so the key could be derived from the cycle counter without the caller noticing.\n\nWith the key known, stable IIDs become directly computable for any prefix (the remaining HMAC inputs — prefix, interface index, interface name, DAD counter — are guessable), and temporary IIDs become linkable after a cheap search over the mixed-in k_uptime_get_32() value. This defeats the properties both features exist to provide: an attacker can track a device across networks and prefixes, and can predict its address inside a /64 without scanning, removing the usual barrier to directly targeting the host. There is no memory-safety, integrity, or availability impact.\n\nThe fix generates the key with sys_csrand_get() and aborts IID generation with -EIO when no cryptographic randomness is available, instead of silently deriving addresses from a predictable key. Both CONFIG_NET_IPV6_IID_STABLE and CONFIG_NET_IPV6_PE are experimental and disabled by default; builds using CONFIG_TEST_RANDOM_GENERATOR remain predictable by design, as sys_csrand_get() is deliberately routed back to the test generator there.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":false,"headline":"IPv6 stable and temporary interface identifiers derived from a non-cryptographic PRNG secret key","id":"CVE-2026-19742","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":null,"year":"2026"},"n_packages":0,"n_references":2,"next":{"headline":"Improper Limitation of a Pathname to a Restricted Directory (Path Traversal) in TeamViewer Desktop Clients","id":"CVE-2026-19743"},"packages":[],"prev":{"headline":"OpenThread joiner autostart uses a publicly documented default Joining Device Credential (PSKd)","id":"CVE-2026-19741"},"products":["zephyr"],"published":"2026-10-26","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-10-26","vendors":["zephyrproject"]},"summary":null,"url":"https://insights.sbomify.com/CVE-2026-19742/"}