# CVE-2026-1678: dns_unpack_name() caches the buffer tailroom once and reuses it while appending DNS labels. As the buffer grows, the…

Source: https://junglewise.ai/threats/cve-2026-1678-dns-unpack-name-caches-the-buffer-tailroom-once-and-reuses-it  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-03-05  
License: CC BY 4.0 with a link back

CVE-2026-1678 · Severity: critical · CVSS 9.4 · Published 2026-03-05

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.

Technologies: [Zephyrproject Zephyr](https://junglewise.ai/threats/technologies/zephyrproject-zephyr). Vendors: [Zephyrproject](https://junglewise.ai/threats/vendors/zephyrproject).

## Quick answers

**Is CVE-2026-1678 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-1678 being exploited in the wild.

**How severe is CVE-2026-1678?** Critical severity, with a CVSS score of 9.4, published 5 March 2026.

**Which products and versions are affected?** Zephyrproject Zephyr. The advisory does not name versions.

**Is there a fix for CVE-2026-1678?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**Am I affected by CVE-2026-1678?** Check whether you run Zephyrproject Zephyr. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- Zephyrproject Zephyr

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