# CVE-2025-7862: TOTOLINK T6 Telnet Service cstecgi.cgi setTelnetCfg missing authentication

> Remote attackers can enable Telnet without authentication on TOTOLINK T6 routers, potentially leading to full device compromise.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/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:** No
- **Published:** 20 Jul 2025
- **Updated:** 22 Jul 2025
- **Also known as:** GHSA-vm25-8x3c-9vc3

## What is CVE-2025-7862?

CVE-2025-7862 is a medium-severity missing authorization vulnerability in TOTOLINK T6, published on 20 Jul 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability has been found in TOTOLINK T6 4.1.5cu.748_B20211015 and classified as critical. Affected by this vulnerability is the function setTelnetCfg of the file /cgi-bin/cstecgi.cgi of the component Telnet Service. The manipulation of the argument telnet_enabled with the input 1 leads to missing authentication. The attack can be launched remotely. The exploit has been disclosed to the public and may be used.

Weakness: CWE-306 (Missing Authentication for Critical Functionality), CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2025-7862?

It affects 1 product.


Products: Totolink T6 Firmware.

## How do I fix CVE-2025-7862?

No fix has been published for CVE-2025-7862 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-7862 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-7862 exists.

## Other vulnerabilities in TOTOLINK T6

- [CVE-2023-7221](https://insights.sbomify.com/CVE-2023-7221/): Totolink T6 HTTP POST Request main buffer overflow (critical 9.8)
- [CVE-2022-38823](https://insights.sbomify.com/CVE-2022-38823/): Hardcoded credentials in n/a (critical 9.8)
- [CVE-2022-38826](https://insights.sbomify.com/CVE-2022-38826/): Command injection in n/a (critical 9.8)
- [CVE-2022-38827](https://insights.sbomify.com/CVE-2022-38827/): Memory corruption in n/a (critical 9.8)
- [CVE-2022-38828](https://insights.sbomify.com/CVE-2022-38828/): Command injection in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-7862 and fix it if it is affected.

What it is: CVE-2025-7862 is a medium-severity missing authorization vulnerability in TOTOLINK T6, published on 20 Jul 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-2025-7862 exists.

Affected product: TOTOLINK T6. 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-2025-7862/ (Markdown: https://insights.sbomify.com/CVE-2025-7862/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-7862
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-7862
- OSV: https://osv.dev/vulnerability/CVE-2025-7862

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-7862/
Summaries are generated and may contain mistakes; the official description above is the record.