# CVE-2025-5623: D-Link DIR-816 qosClassifier stack-based overflow

> Remote attackers can exploit a stack-based buffer overflow in the qosClassifier function of unsupported D-Link DIR-816 routers to execute arbitrary code.

- **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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Jun 2025
- **Updated:** 5 Jun 2025
- **Also known as:** GHSA-v8p3-7jrm-c3rr

## What is CVE-2025-5623?

CVE-2025-5623 is a critical memory corruption vulnerability in Dlink Dir-816 Firmware, published on 5 Jun 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability was found in D-Link DIR-816 1.10CNB05. It has been classified as critical. This affects the function qosClassifier of the file /goform/qosClassifier. The manipulation of the argument dip_address/sip_address leads to stack-based buffer overflow. It is possible to initiate the attack remotely. The exploit has been disclosed to the public and may be used. This vulnerability only affects products that are no longer supported by the maintainer.

Weakness: CWE-121 (Stack-based Buffer Overflow), CWE-787 (Out-of-bounds Write), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2025-5623?

It affects 1 product.


Products: Dlink Dir-816 Firmware.

## How do I fix CVE-2025-5623?

No fix has been published for CVE-2025-5623 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-5623 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-5623 exists.

## Other vulnerabilities in Dlink Dir-816 Firmware

- [CVE-2025-45931](https://insights.sbomify.com/CVE-2025-45931/): Command injection in n/a (critical 9.8)
- [CVE-2024-57684](https://insights.sbomify.com/CVE-2024-57684/): Missing authorization in n/a (critical 9.8)
- [CVE-2023-24331](https://insights.sbomify.com/CVE-2023-24331/): Command injection in n/a (critical 9.8)
- [CVE-2024-24321](https://insights.sbomify.com/CVE-2024-24321/): Command injection in n/a (critical 9.8)
- [CVE-2023-39637](https://insights.sbomify.com/CVE-2023-39637/): Command injection in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-5623 and fix it if it is affected.

What it is: CVE-2025-5623 is a critical memory corruption vulnerability in Dlink Dir-816 Firmware, published on 5 Jun 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-5623 exists.

Affected product: Dlink Dir-816 Firmware. 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-2025-5623/ (Markdown: https://insights.sbomify.com/CVE-2025-5623/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-5623
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-5623
- OSV: https://osv.dev/vulnerability/CVE-2025-5623

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-5623/
Summaries are generated and may contain mistakes; the official description above is the record.