# CVE-2023-34100: Out-of-Bounds Read in contiki-ng

> An out-of-bounds read in Contiki-NG's TCP MSS handling allows attackers to read memory or cause crashes on IoT devices.

- **Severity:** High 7.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Jun 2023
- **Updated:** 6 Jan 2025
- **Also known as:** GHSA-3v7c-jq9x-cmph

## What is CVE-2023-34100?

CVE-2023-34100 is a high-severity memory corruption vulnerability in contiki-ng, published on 9 Jun 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Contiki-NG is an open-source, cross-platform operating system for IoT devices. When reading the TCP MSS option value from an incoming packet, the Contiki-NG OS does not verify that certain buffer indices to read from are within the bounds of the IPv6 packet buffer, uip_buf. In particular, there is a 2-byte buffer read in the module os/net/ipv6/uip6.c. The buffer is indexed using 'UIP_IPTCPH_LEN + 2 + c' and 'UIP_IPTCPH_LEN + 3 + c', but the uip_buf buffer may not have enough data, resulting in a 2-byte read out of bounds. The problem has been patched in the "develop" branch of Contiki-NG, and is expected to be included in release 4.9. Users are advised to watch for the 4.9 release and to upgrade when it becomes available. There are no workarounds for this vulnerability aside from manually patching with the diff in commit `cde4e9839`.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2023-34100?

It affects 1 product.


Products: Contiki-Ng Contiki-Ng.

## How do I fix CVE-2023-34100?

No fix has been published for CVE-2023-34100 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-34100 being exploited?

There is no known exploitation of CVE-2023-34100 in the wild and no public exploit code.

## Other vulnerabilities in contiki-ng

- [CVE-2018-19417](https://insights.sbomify.com/CVE-2018-19417/): Memory corruption in n/a (critical 10.0)
- [CVE-2023-30546](https://insights.sbomify.com/CVE-2023-30546/): Contiki-NG has off-by-one error in Antelope DBMS (critical 9.8)
- [CVE-2020-24336](https://insights.sbomify.com/CVE-2020-24336/): Memory corruption in n/a (critical 9.8)
- [CVE-2020-14934](https://insights.sbomify.com/CVE-2020-14934/): Memory corruption in n/a (critical 9.8)
- [CVE-2020-14935](https://insights.sbomify.com/CVE-2020-14935/): Memory corruption in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-34100 and fix it if it is affected.

What it is: CVE-2023-34100 is a high-severity memory corruption vulnerability in contiki-ng, published on 9 Jun 2023. 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-2023-34100 in the wild and no public exploit code.

Affected product: contiki-ng. 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-2023-34100/ (Markdown: https://insights.sbomify.com/CVE-2023-34100/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-34100
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-34100
- OSV: https://osv.dev/vulnerability/CVE-2023-34100

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-34100/
Summaries are generated and may contain mistakes; the official description above is the record.