# CVE-2020-35571: MantisBT XSS in manage_custom_field_update.php

> Attackers can inject malicious scripts via unsanitized custom field names in MantisBT, potentially leading to session hijacking or code execution.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 22 Feb 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-cvrm-cr3m-qj92

## What is CVE-2020-35571?

CVE-2020-35571 is a medium-severity cross-site scripting vulnerability in Mantisbt Mantisbt, published on 22 Feb 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

An issue was discovered in MantisBT through 2.24.3. In the helper_ensure_confirmed call in manage_custom_field_update.php, the custom field name is not sanitized. This may be problematic depending on CSP settings.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2020-35571?

2 open source packages ship an affected version, including mantisbt/mantisbt. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mantisbt/mantisbt` | Packagist | All versions | 2.25.0 |
| `mantisbt/mantisbt` | Packagist | All versions | 2.25.0 |

Products: Mantisbt Mantisbt.

## How do I fix CVE-2020-35571?

Upgrade mantisbt/mantisbt to 2.25.0 or later.

## Is CVE-2020-35571 being exploited?

There is no known exploitation of CVE-2020-35571 in the wild and no public exploit code.

## Other vulnerabilities in Mantisbt Mantisbt

- [CVE-2019-15074](https://insights.sbomify.com/CVE-2019-15074/): MantisBT allows cross-site scripting (XSS) via crafted filename (critical 9.6)
- [CVE-2026-30849](https://insights.sbomify.com/CVE-2026-30849/): MantisBT SOAP API has an authentication bypass vulnerability on MySQL (critical 9.3)
- [CVE-2025-47776](https://insights.sbomify.com/CVE-2025-47776/): MantisBT: Authentication bypass for some passwords due to PHP type juggling (high 8.8)
- [CVE-2017-7615](https://insights.sbomify.com/CVE-2017-7615/): MantisBT allows arbitrary password reset (high 8.8)
- [CVE-2026-33517](https://insights.sbomify.com/CVE-2026-33517/): MantisBT Vulnerable to Stored HTML Injection in Tag Delete Confirmation (high 8.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-35571 and fix it if it is affected.

What it is: CVE-2020-35571 is a medium-severity cross-site scripting vulnerability in Mantisbt Mantisbt, published on 22 Feb 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2020-35571 in the wild and no public exploit code.

Affected packages and fixed versions:
- mantisbt/mantisbt (Packagist): affected all versions; fixed in 2.25.0
- mantisbt/mantisbt (Packagist): affected all versions; fixed in 2.25.0

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-2020-35571/ (Markdown: https://insights.sbomify.com/CVE-2020-35571/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-35571
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-35571
- OSV: https://osv.dev/vulnerability/CVE-2020-35571

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-35571/
Summaries are generated and may contain mistakes; the official description above is the record.