# CVE-2021-20151: Auth bypass in Trendnet AC2600 TEW-827DRU

> Attackers can hijack web sessions by spoofing IP addresses due to IP-based session management, allowing unauthorized access to the router interface.

- **Severity:** Critical 10.0 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 30 Dec 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-hqq7-2rg7-fxx5

## What is CVE-2021-20151?

CVE-2021-20151 is a critical authentication bypass vulnerability in Trendnet AC2600 TEW-827DRU, published on 30 Dec 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Trendnet AC2600 TEW-827DRU version 2.08B01 contains a flaw in the session management for the device. The router's management software manages web sessions based on IP address rather than verifying client cookies/session tokens/etc. This allows an attacker (whether from a different computer, different web browser on the same machine, etc.) to take over an existing session. This does require the attacker to be able to spoof or take over original IP address of the original user's session.

Weakness: CWE-384 (Session Fixation)

## Which versions are affected by CVE-2021-20151?

It affects 1 product.


Products: Trendnet Tew-827dru Firmware.

## How do I fix CVE-2021-20151?

No fix has been published for CVE-2021-20151 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-20151 being exploited?

There is no known exploitation of CVE-2021-20151 in the wild and no public exploit code.

## Other vulnerabilities in Trendnet AC2600 TEW-827DRU

- [CVE-2024-28354](https://insights.sbomify.com/CVE-2024-28354/): Command injection in n/a (critical 10.0)
- [CVE-2021-20149](https://insights.sbomify.com/CVE-2021-20149/): Missing authorization in Trendnet AC2600 TEW-827DRU (critical 9.8)
- [CVE-2021-20155](https://insights.sbomify.com/CVE-2021-20155/): Hardcoded credentials in Trendnet AC2600 TEW-827DRU (critical 9.8)
- [CVE-2021-20158](https://insights.sbomify.com/CVE-2021-20158/): Auth bypass in Trendnet AC2600 TEW-827DRU (critical 9.8)
- [CVE-2020-14080](https://insights.sbomify.com/CVE-2020-14080/): Memory corruption in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-20151 and fix it if it is affected.

What it is: CVE-2021-20151 is a critical authentication bypass vulnerability in Trendnet AC2600 TEW-827DRU, published on 30 Dec 2021. 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-2021-20151 in the wild and no public exploit code.

Affected product: Trendnet AC2600 TEW-827DRU. 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-2021-20151/ (Markdown: https://insights.sbomify.com/CVE-2021-20151/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-20151
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-20151
- OSV: https://osv.dev/vulnerability/CVE-2021-20151

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-20151/
Summaries are generated and may contain mistakes; the official description above is the record.