CVE-2026-12633
IPv6 6LoWPAN 6CO parsing bug allows adjacent-host memory corruption and DoS
Is CVE-2026-12633 being exploited?
Not confirmed. CVE-2026-12633 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.21% probability of exploitation in the next 30 days.
How severe is CVE-2026-12633?
CVE-2026-12633 is rated High with a CVSS score of 8.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-12633?
Yes. A fix has been recorded for CVE-2026-12633. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-12633 affect?
CVE-2026-12633 affects Zephyr OS (subsys/net IPv6 6LoWPAN), 6LoWPAN-capable embedded/IoT devices with CONFIG_NET_6LO_CONTEXT enabled. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-12633?
Apply vendor patch; filter/block untrusted link-local RAs; disable CONFIG_NET_6LO_CONTEXT if unused
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Adjacent attacker sends crafted ICMPv6 Router Advertisement with 6CO to trigger out-of-bounds memset, zeroing kernel memory and causing reliable DoS and integrity loss.
Patch when possible
- affected>= 1.8.0 and < 4.4.2
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.