# CVE-2026-8836: lwIP snmpv3 USM snmp_msg.c snmp_parse_inbound_frame stack-based overflow

> Remote attackers can trigger a stack-based buffer overflow in the lwIP SNMPv3 USM handler, potentially leading to code execution or denial of service.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 May 2026
- **Updated:** 22 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-8836, GHSA-3w8m-3w76-f6mh, OESA-2026-2480, UBUNTU-CVE-2026-8836

## What is CVE-2026-8836?

CVE-2026-8836 is a critical memory corruption vulnerability in lwIP, published on 18 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability was found in lwIP up to 2.2.1. Affected is the function snmp_parse_inbound_frame of the file src/apps/snmp/snmp_msg.c of the component snmpv3 USM Handler. Performing a manipulation of the argument msgAuthenticationParameters results in stack-based buffer overflow. The attack may be initiated remotely. The patch is named 0c957ec03054eb6c8205e9c9d1d05d90ada3898c. It is suggested to install a patch to address this issue. Two separate issue reports were submitted to the project. Their processing was merged as a duplicate.

Weakness: CWE-121 (Stack-based Buffer Overflow), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-8836?


## How do I fix CVE-2026-8836?

Apply the vendor's patch.

## Is CVE-2026-8836 being exploited?

There is no known exploitation of CVE-2026-8836 in the wild and no public exploit code.

Public exploit code:

- CVE-2026-8836 — lwIP SNMPv3 stack-based buffer overflow PoC (CVSS 9.8) (github_poc): https://github.com/Hunt-Benito/lwip-snmpv3-stack-overflow-cve-2026-8836-critical-embedded-rce

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-8836 and fix it if it is affected.

What it is: CVE-2026-8836 is a critical memory corruption vulnerability in lwIP, published on 18 May 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-2026-8836 in the wild and no public exploit code.

Affected product: lwIP. 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-2026-8836/ (Markdown: https://insights.sbomify.com/CVE-2026-8836/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-8836
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-8836
- OSV: https://osv.dev/vulnerability/CVE-2026-8836

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-8836/
Summaries are generated and may contain mistakes; the official description above is the record.