# CVE-2021-23845: B426 Web Configuration Authentication Bypass

> An attacker can hijack sessions on the B426 web configuration page, allowing unauthorized access to the device settings.

- **Severity:** High 8.0 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 18 Jun 2021
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-4fvc-h857-qw9g

## What is CVE-2021-23845?

CVE-2021-23845 is a high-severity authentication bypass vulnerability in Bosch B426 Firmware, published on 18 Jun 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

This vulnerability could allow an attacker to hijack a session while a user is logged in the configuration web page. This vulnerability was discovered by a security researcher in B426 and found during internal product tests in B426-CN/B429-CN, and B426-M and has been fixed already starting from version 3.08 on, which was released on June 2019.

Weakness: CWE-284 (Improper Access Control)

## Which versions are affected by CVE-2021-23845?

It affects 4 products.


Products: Bosch B426-Cn Firmware, Bosch B426-M Firmware, Bosch B426 Firmware, Bosch B429-Cn Firmware.

## How do I fix CVE-2021-23845?

No fix has been published for CVE-2021-23845 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-23845 being exploited?

There is no known exploitation of CVE-2021-23845 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-23845 and fix it if it is affected.

What it is: CVE-2021-23845 is a high-severity authentication bypass vulnerability in Bosch B426 Firmware, published on 18 Jun 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-23845 in the wild and no public exploit code.

Affected product: Bosch B426 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-2021-23845/ (Markdown: https://insights.sbomify.com/CVE-2021-23845/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-23845
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-23845
- OSV: https://osv.dev/vulnerability/CVE-2021-23845

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-23845/
Summaries are generated and may contain mistakes; the official description above is the record.