CVE-2026-1678: zephyrproject-rtos Zephyr · Out-of-bounds Write
Affects zephyrproject-rtos ZephyrSource CVE Database V5
Not known to be exploited · CVSS 9.4 Critical · fixed in 4.3.1 : patch zephyrproject-rtos Zephyr as a priority.
Data as of 29 Oct 2026, 19:04 UTC
Contested
Critical score, yet low EPSS after six months- EPSS
- 0.3% chance of exploitation in 30 days – higher than 34% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 4.3.1, 4.2.2, 3.7.2
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 5 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade zephyrproject-rtos Zephyr to 4.3.1, 4.2.2 or 3.7.2.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| zephyrproject-rtosZephyr | Affected
| Fixed in
|
| zephyrproject-rtosZephyr | Affected
| Fixed in
|
| zephyrproject-rtosZephyr | Affected
| Fixed in
|
GitHubzephyrproject-rtos/zephyrpkg:github/zephyrproject-rtos/zephyrOther threats | Affected
| Fixed in– |
GitHubZephyrpkg:github/ZephyrOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
To mitigate CVE-2026-1678, organizations should prioritize updating Zephyr to a patched version once available from the vendor or community. In the interim, disabling CONFIG_DNS_RESOLVER if DNS resolution is not required can eliminate the attack surface. Network-level defenses should be employed, such as filtering and validating DNS responses to block malicious packets before they reach vulnerable devices. Implementing DNS over TLS or DNSSEC can reduce the risk of malicious DNS responses. Additionally, enabling assertions during development and testing can help detect memory corruption issues early. For embedded devices, consider applying runtime memory protection mechanisms if supported. Monitoring network traffic for anomalous DNS responses and maintaining an inventory of Zephyr-based devices will aid in rapid response. Finally, coordinate with device manufacturers and vendors to ensure timely firmware updates and security patches are deployed.
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.