# CVE-2026-8618: Pre-Authentication Stack-based Buffer Overflow Remote Code Execution in TDDPv2 Subtype 0x91 on Deco M9 Plus

> An adjacent unauthenticated attacker can achieve remote code execution or cause denial of service via a stack-based buffer overflow in the TDDPv2 service.

- **Severity:** High 7.7 (`CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 1 Oct 2026
- **Updated:** 1 Oct 2026
- **Also known as:** GHSA-fxpm-c4jc-x283

## What is CVE-2026-8618?

CVE-2026-8618 is a high-severity memory corruption vulnerability in TP-Link Systems Inc. Deco M9 Plus V2, published on 1 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A stack-based buffer overflow vulnerability exists in the TDDPv2 service (/usr/bin/tddp) on Deco M9 Plus due to insufficient validation of decrypted request data length before it is copied into a fixed-size stack buffer in the subtype 0x91 handler. Successful exploitation may allow an adjacent, unauthenticated attacker to cause a denial of service or achieve arbitrary code execution during the device setup phase through crafted TDDP packets.

Weakness: CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2026-8618?


## How do I fix CVE-2026-8618?

No fix has been published for CVE-2026-8618 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-8618 being exploited?

There is no known exploitation of CVE-2026-8618 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-8618 and fix it if it is affected.

What it is: CVE-2026-8618 is a high-severity memory corruption vulnerability in TP-Link Systems Inc. Deco M9 Plus V2, published on 1 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-8618 in the wild and no public exploit code.

Affected product: TP-Link Systems Inc. Deco M9 Plus V2. 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-2026-8618/ (Markdown: https://insights.sbomify.com/CVE-2026-8618/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-8618
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-8618
- OSV: https://osv.dev/vulnerability/CVE-2026-8618

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-8618/
Summaries are generated and may contain mistakes; the official description above is the record.