# CVE-2026-4253: Tenda AC8 Web UploadCfg route_set_user_policy_rule os command injection

> Remote attackers can execute arbitrary OS commands on Tenda AC8 routers via the UploadCfg interface, requiring authentication.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Mar 2026
- **Updated:** 16 Mar 2026
- **Also known as:** GHSA-6g93-h28j-6gjp

## What is CVE-2026-4253?

CVE-2026-4253 is a medium-severity command injection vulnerability in Tenda Ac8 Firmware, published on 16 Mar 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

A security flaw has been discovered in Tenda AC8 16.03.50.11. This affects the function route_set_user_policy_rule of the file /cgi-bin/UploadCfg of the component Web Interface. The manipulation of the argument wans.policy.list1 results in os command injection. It is possible to launch the attack remotely. The exploit has been released to the public and may be used for attacks.

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command), CWE-77 (Improper Neutralization of Special Elements used in a Command)

## Which versions are affected by CVE-2026-4253?

It affects 1 product.


Products: Tenda Ac8 Firmware.

## How do I fix CVE-2026-4253?

No fix has been published for CVE-2026-4253 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-4253 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-4253 exists.

Public exploit code:

- Non-destructive vulnerability scanner for NGINX HTTP/3 (ngx_http_v3_module). It ONLY performs a safe probe: opens an HTTP/3 (QUIC) connection, sends a single HEAD request and inspects the `Server` response header. It NEVER attempts to reopen a QPACK encoder stream or trigger the use-after-free. (github_poc): https://github.com/renzi25031469/CVE-2026-4253-Scanner

## Other vulnerabilities in Tenda Ac8 Firmware

- [CVE-2025-29100](https://insights.sbomify.com/CVE-2025-29100/): Memory corruption in n/a (critical 9.8)
- [CVE-2025-25663](https://insights.sbomify.com/CVE-2025-25663/): Memory corruption in n/a (critical 9.8)
- [CVE-2025-25664](https://insights.sbomify.com/CVE-2025-25664/): Memory corruption in n/a (critical 9.8)
- [CVE-2025-25667](https://insights.sbomify.com/CVE-2025-25667/): Memory corruption in n/a (critical 9.8)
- [CVE-2025-25668](https://insights.sbomify.com/CVE-2025-25668/): Memory corruption in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-4253 and fix it if it is affected.

What it is: CVE-2026-4253 is a medium-severity command injection vulnerability in Tenda Ac8 Firmware, published on 16 Mar 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-4253 exists.

Affected product: Tenda Ac8 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-2026-4253/ (Markdown: https://insights.sbomify.com/CVE-2026-4253/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-4253
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-4253
- OSV: https://osv.dev/vulnerability/CVE-2026-4253

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-4253/
Summaries are generated and may contain mistakes; the official description above is the record.