# CVE-2026-49868: Integer overflow in RIOT

> A malicious DHCPv6 server can trigger a size_t underflow in RIOT OS, causing out-of-bounds heap reads that may crash the device or leak memory.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Oct 2026
- **Updated:** 21 Oct 2026
- **Also known as:** GHSA-p3fx-9qcg-jmcf

## What is CVE-2026-49868?

CVE-2026-49868 is a critical vulnerability in RIOT-OS RIOT, published on 16 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

RIOT is an open-source microcontroller operating system designed for Internet of Things devices and other embedded systems. Prior to 2026.07, _parse_reply() in sys/net/application_layer/dhcpv6/client.c omits minimum-length validation before passing IA_PD and IA_NA option bodies to sub-option parsers. A malicious or compromised DHCPv6 server can send a REPLY with an option length smaller than the required structure while MODULE_DHCPV6_CLIENT_IA_PD is enabled, causing _parse_ia_pd_option to read past the option body, size_t underflow, and unbounded out-of-bounds heap reads that can crash the device and may expose or corrupt memory. This issue is fixed in version 2026.07.

Weakness: CWE-191 (Integer Underflow (Wrap or Wraparound)), CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-49868?


## How do I fix CVE-2026-49868?

No fix has been published for CVE-2026-49868 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-49868 being exploited?

There is no known exploitation of CVE-2026-49868 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-49868 and fix it if it is affected.

What it is: CVE-2026-49868 is a critical vulnerability in RIOT-OS RIOT, published on 16 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-49868 in the wild and no public exploit code.

Affected product: RIOT-OS RIOT. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-49868/ (Markdown: https://insights.sbomify.com/CVE-2026-49868/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-49868
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-49868
- OSV: https://osv.dev/vulnerability/CVE-2026-49868

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-49868/
Summaries are generated and may contain mistakes; the official description above is the record.