# CVE-2020-24355: Privilege escalation in n/a

> Attackers can escalate privileges by manipulating JSON fields during account creation on Zyxel VMG5313-B30B routers.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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:** 2 Sep 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-2f6p-fvp2-42p6

## What is CVE-2020-24355?

CVE-2020-24355 is a critical vulnerability in n/a, published on 2 Sep 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Zyxel VMG5313-B30B router on firmware 5.13(ABCJ.6)b3_1127, and possibly older versions of firmware are affected by insecure permissions which allows regular and other users to create new users with elevated privileges. This is done by changing "FirstIndex" field in JSON that is POST-ed during account creation. Similar may also be possible with account deletion.

Weakness: CWE-732 (Incorrect Permission Assignment for Critical Resource)

## Which versions are affected by CVE-2020-24355?

It affects 1 product.


Products: Zyxel Vmg5313-B30b Firmware.

## How do I fix CVE-2020-24355?

No fix has been published for CVE-2020-24355 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-24355 being exploited?

There is no known exploitation of CVE-2020-24355 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2020-24354](https://insights.sbomify.com/CVE-2020-24354/): Command injection in n/a (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-24355 and fix it if it is affected.

What it is: CVE-2020-24355 is a critical vulnerability in n/a, published on 2 Sep 2020. 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-2020-24355 in the wild and no public exploit code.

Affected product: n/a. 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-2020-24355/ (Markdown: https://insights.sbomify.com/CVE-2020-24355/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-24355
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-24355
- OSV: https://osv.dev/vulnerability/CVE-2020-24355

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-24355/
Summaries are generated and may contain mistakes; the official description above is the record.