Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-1678 is a critical-severity Out-of-bounds Write (CWE-787) vulnerability in Zephyrproject Zephyr. Its CVSS base score is 9.4 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 30th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-1678 is an out-of-bounds write vulnerability in the dns_unpack_name() function of the Zephyr RTOS. The function caches the buffer tailroom once and reuses this value while appending DNS labels, leading to an incorrect cached size as the buffer grows. Consequently, the final null terminator can be written past the buffer end. This affects Zephyr RTOS builds with CONFIG_DNS_RESOLVER enabled and assertions disabled, which is the default configuration. The vulnerability is classified under CWE-787 and has a CVSS 3.1 base score of 9.4 (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H).
A remote, unauthenticated attacker can exploit this vulnerability over the network by crafting and sending a malicious DNS response to a vulnerable system. No user interaction or special privileges are required. Exploitation triggers the out-of-bounds write, potentially allowing the attacker to corrupt memory, cause denial of service, or manipulate data integrity, with high impacts on integrity and availability alongside low confidentiality impact.
Mitigation details and patches are documented in the Zephyr Project security advisory at https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-536f-h63g-hj42.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-9792
Vulnerability Data
dns_unpack_name() caches the buffer tailroom once and reuses it while appending DNS labels. As the buffer grows, the cached size becomes incorrect, and the final null terminator can be written past the buffer. With assertions disabled (default), a malicious DNS…
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response can trigger an out-of-bounds write when CONFIG_DNS_RESOLVER is enabled.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation (including fuzzing and bounds checks) finds out-of-bounds write flaws before deployment.
Requiring documented secure-development standards and tools can mandate bounds-checked coding practices that avoid the weakness.
Input validation can structurally reject or sanitize data that would otherwise trigger an out-of-bounds write.
Memory-protection mechanisms limit the exploitability and blast radius of a successful out-of-bounds write.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure-development practices (static analysis, bounds checking, code review) are the primary means of preventing out-of-bounds writes.
Vulnerability scanning and recording can discover out-of-bounds write flaws so they can be remediated.
Patching or replacing vulnerable software directly eliminates known instances of this coding weakness.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development and acceptance can detect and prevent out-of-bounds write defects.
Secure development life cycle mandates practices that prevent out-of-bounds writes.
Application security requirements can specify bounds-checking and safe memory handling.
Secure architecture and engineering principles reduce the likelihood of buffer overflows.
Secure coding directly addresses out-of-bounds writes through language choice and coding standards.
Change management can enforce review gates that catch unsafe memory operations before deployment.