# CVE-2025-34468: libcoap Stack-Based Buffer Overflow in Address Resolution DoS or Potential RCE

> A stack-based buffer overflow in libcoap allows remote attackers to cause denial of service or potentially execute code when proxy logic is enabled.

- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 31 Dec 2025
- **Updated:** 14 Jul 2026
- **Also known as:** DEBIAN-CVE-2025-34468, GHSA-rj9f-6c28-qf6x, UBUNTU-CVE-2025-34468

## What is CVE-2025-34468?

CVE-2025-34468 is a high-severity memory corruption vulnerability in libcoap, published on 31 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

libcoap versions up to and including 4.3.5, prior to commit 30db3ea, contain a stack-based buffer overflow in address resolution when attacker-controlled hostname data is copied into a fixed 256-byte stack buffer without proper bounds checking. A remote attacker can trigger a crash and potentially achieve remote code execution depending on compiler options and runtime memory protections. Exploitation requires the proxy logic to be enabled (i.e., the proxy request handling code path in an application using libcoap).

Weakness: CWE-787 (Out-of-bounds Write), CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2025-34468?

It affects 1 product.


Products: Libcoap Libcoap.

## How do I fix CVE-2025-34468?

Apply the vendor's patch.

## Is CVE-2025-34468 being exploited?

There is no known exploitation of CVE-2025-34468 in the wild and no public exploit code.

## Other vulnerabilities in libcoap

- [CVE-2026-29013](https://insights.sbomify.com/CVE-2026-29013/): libcoap Out-of-Bounds Read in OSCORE CBOR Unwrap Handling (high 8.8)
- [CVE-2025-65493](https://insights.sbomify.com/CVE-2025-65493/): Null dereference in n/a (high 7.5)
- [CVE-2025-65494](https://insights.sbomify.com/CVE-2025-65494/): Null dereference in n/a (high 7.5)
- [CVE-2025-65495](https://insights.sbomify.com/CVE-2025-65495/): Integer overflow in n/a (high 7.5)
- [CVE-2023-30362](https://insights.sbomify.com/CVE-2023-30362/): Information disclosure in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-34468 and fix it if it is affected.

What it is: CVE-2025-34468 is a high-severity memory corruption vulnerability in libcoap, published on 31 Dec 2025. 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-2025-34468 in the wild and no public exploit code.

Affected product: libcoap. 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-2025-34468/ (Markdown: https://insights.sbomify.com/CVE-2025-34468/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-34468
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-34468
- OSV: https://osv.dev/vulnerability/CVE-2025-34468

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-34468/
Summaries are generated and may contain mistakes; the official description above is the record.