# CVE-2023-49792: Bruteforce protection can be bypassed with misconfigured proxy

> Attackers can bypass brute-force protection in Nextcloud Server when a reverse proxy is misconfigured, allowing excessive authentication attempts.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 22 Dec 2023
- **Updated:** 27 Aug 2024
- **Also known as:** GHSA-5j2p-q736-hw98

## What is CVE-2023-49792?

CVE-2023-49792 is a medium-severity vulnerability in Nextcloud Nextcloud Server, published on 22 Dec 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. In Nextcloud Server prior to versions 26.0.9 and 27.1.4; as well as Nextcloud Enterprise Server prior to versions 23.0.12.13, 24.0.12.9, 25.0.13.4, 26.0.9, and 27.1.4; when a (reverse) proxy is configured as trusted proxy the server could be tricked into reading a wrong remote address for an attacker, allowing them executing authentication attempts than intended. Nextcloud Server versions 26.0.9 and 27.1.4 and Nextcloud Enterprise Server versions 23.0.12.13, 24.0.12.9, 25.0.13.4, 26.0.9, and 27.1.4 contain a patch for this issue. No known workarounds are available.

Weakness: CWE-307 (Improper Restriction of Excessive Authentication Attempts)

## Which versions are affected by CVE-2023-49792?

It affects 1 product.


Products: Nextcloud Nextcloud Server.

## How do I fix CVE-2023-49792?

No fix has been published for CVE-2023-49792 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-49792 being exploited?

There is no known exploitation of CVE-2023-49792 in the wild and no public exploit code.

Public exploit code:

- A project analysis of CVE-2023-49792, inspired by a HackerOne report I have recently come across. (github_poc): https://github.com/CStockdale1/nextcloud-cve-2023-49792-research

## Other vulnerabilities in Nextcloud Nextcloud Server

- [CVE-2021-32802](https://insights.sbomify.com/CVE-2021-32802/): Preview generation used third-party library not suited for user-generated content in Nextcloud server (critical 9.3)
- [CVE-2023-26482](https://insights.sbomify.com/CVE-2023-26482/): Scope of workflow operations is not validated in nextcloud server (critical 9.1)
- [CVE-2018-3775](https://insights.sbomify.com/CVE-2018-3775/): Auth bypass in Nextcloud Server (high 8.8)
- [CVE-2023-35172](https://insights.sbomify.com/CVE-2023-35172/): Nextcloud Server password reset endpoint is not brute force protected (high 8.7)
- [CVE-2023-32320](https://insights.sbomify.com/CVE-2023-32320/): Nextcloud Server's brute force protection allows someone to send more requests than intended (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-49792 and fix it if it is affected.

What it is: CVE-2023-49792 is a medium-severity vulnerability in Nextcloud Nextcloud Server, published on 22 Dec 2023. 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-2023-49792 in the wild and no public exploit code.

Affected product: Nextcloud Nextcloud Server. 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-2023-49792/ (Markdown: https://insights.sbomify.com/CVE-2023-49792/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-49792
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-49792
- OSV: https://osv.dev/vulnerability/CVE-2023-49792

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-49792/
Summaries are generated and may contain mistakes; the official description above is the record.