# CVE-2026-44657: MantisBT: Stored XSS in File Download

> An attacker can execute arbitrary code via stored XSS by uploading crafted XHTML attachments in MantisBT.

- **Severity:** High 7.5 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N`)
- **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:** Yes
- **Published:** 28 May 2026
- **Updated:** 29 May 2026
- **Also known as:** GHSA-p6fr-rxq7-xcg8

## What is CVE-2026-44657?

CVE-2026-44657 is a high-severity cross-site scripting vulnerability in mantisbt, published on 28 May 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

Mantis Bug Tracker (MantisBT) is an open source issue tracker. Prior to 2.28.2, using show_inline=1 parameter and a valid file_show_inline_token CSRF token on file_download.php, an attacker can execute code by uploading a crafted XHTML attachment referencing a JavaScript attachment. This vulnerability is fixed in 2.28.2.

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

## Which versions are affected by CVE-2026-44657?

2 open source packages ship an affected version, including mantisbt/mantisbt.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mantisbt/mantisbt` | Packagist | All versions | 2.28.2 |
| `mantisbt/mantisbt` | Packagist | All versions | 2.28.2 |

## How do I fix CVE-2026-44657?

Upgrade mantisbt/mantisbt to 2.28.2 or later.

## Is CVE-2026-44657 being exploited?

There is no known exploitation of CVE-2026-44657 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-44657 and fix it if it is affected.

What it is: CVE-2026-44657 is a high-severity cross-site scripting vulnerability in mantisbt, published on 28 May 2026. 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-2026-44657 in the wild and no public exploit code.

Affected packages and fixed versions:
- mantisbt/mantisbt (Packagist): affected all versions; fixed in 2.28.2
- mantisbt/mantisbt (Packagist): affected all versions; fixed in 2.28.2

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-2026-44657/ (Markdown: https://insights.sbomify.com/CVE-2026-44657/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-44657
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-44657
- OSV: https://osv.dev/vulnerability/CVE-2026-44657

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-44657/
Summaries are generated and may contain mistakes; the official description above is the record.