Critical · CVSS 9.4CVE-2026-1678

dns: memory‑safety issue in the DNS name parserCVE-2026-1678

Answer in brief

CVE-2026-1678 records a Critical severity (CVSS 9.4) vulnerability in dns: memory‑safety issue in the DNS name parser. The current sources do not mark it as known exploited. The current feed maps zephyrproject-rtos/Zephyr (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Mar 5, 2026Updated Oct 15, 2026Source checked Oct 15, 2026First seen by HOL Oct 15, 2026Material review Oct 15, 2026

Upstream Advisory

Key facts

Risk: Critical · CVSS 9.4
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 9.4. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps zephyrproject-rtos/Zephyr (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
zephyrproject-rtos/Zephyrgeneric	>=* <3.7.2 \|\| >=4.0.0 <4.2.2 \|\| >=4.3.0 <4.3.1	3.7.2, 4.2.2, 4.3.1

Recommended response

Check inventory. Check lockfiles and deployed manifests for zephyrproject-rtos/Zephyr.
Review the reported fix. Update zephyrproject-rtos/Zephyr to 3.7.2 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Mar 5, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Oct 15, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Oct 15, 2026

Sources and claim methodology

GitHub security advisorygithub.com

Upstream source description

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 response can trigger an out-of-bounds write when CONFIG_DNS_RESOLVER is enabled.

Quoted source text, attributed separately from HOL analysis.