# CVE-2026-33548: MantisBT has Stored HTML Injection / XSS when displaying Tags in Timeline

> Attackers can inject HTML or JavaScript via tag names in the timeline, potentially executing arbitrary code if CSP permits.

- **Severity:** High 8.6 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/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:** 23 Mar 2026
- **Updated:** 24 Mar 2026
- **Also known as:** GHSA-73vx-49mv-v8w5

## What is CVE-2026-33548?

CVE-2026-33548 is a high-severity cross-site scripting vulnerability in Mantisbt Mantisbt, published on 23 Mar 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. In version 2.28.0, improper escaping of tag names retrieved from History in Timeline (my_view_page.php) allows an attacker to inject HTML and, if CSP settings permit, achieve execution of arbitrary JavaScript, when displaying a tag that has been renamed or deleted. Version 2.28.1 contains a patch. Workarounds include editing offending History entries (using SQL) and wrapping `$this->tag_name` in a string_html_specialchars() call in IssueTagTimelineEvent::html().

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

## Which versions are affected by CVE-2026-33548?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mantisbt/mantisbt` | Packagist | From 2.28.0 | 2.28.2 |
| `mantisbt/mantisbt` | Packagist | From 2.28.0 | 2.28.2 |

Products: Mantisbt Mantisbt.

## How do I fix CVE-2026-33548?

Upgrade mantisbt/mantisbt to 2.28.2 or later.

## Is CVE-2026-33548 being exploited?

There is no known exploitation of CVE-2026-33548 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-2026-33548 and fix it if it is affected.

What it is: CVE-2026-33548 is a high-severity cross-site scripting vulnerability in Mantisbt Mantisbt, published on 23 Mar 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-2026-33548 in the wild and no public exploit code.

Affected packages and fixed versions:
- mantisbt/mantisbt (Packagist): affected from 2.28.0; fixed in 2.28.2
- mantisbt/mantisbt (Packagist): affected from 2.28.0; 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-2026-33548/ (Markdown: https://insights.sbomify.com/CVE-2026-33548/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33548
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33548
- OSV: https://osv.dev/vulnerability/CVE-2026-33548

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33548/
Summaries are generated and may contain mistakes; the official description above is the record.