CVE-2026-44657: Mantisbt/mantisbt Cross-Site Scripting Vulnerability

HIGH
Advisory Identifier: GHSA-p6fr-rxq7-xcg8
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CWE-79
Published
Advisory Summary

CVE-2026-44657 is a HIGH cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Mantisbt/mantisbt libraries in the Packagist ecosystem. The issue involves mantisbt vulnerable to stored xss in file download. Remediation is available by upgrading affected packages to version 2.28.2.

CVE-2026-44657 at a Glance

CVE Identifier CVE-2026-44657
GHSA Identifier GHSA-p6fr-rxq7-xcg8
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Mantisbt/mantisbt
Package Ecosystem Packagist
Published Date
Last Updated

How to Fix CVE-2026-44657

To remediate this vulnerability, upgrade all affected Mantisbt/mantisbt dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

mantisbt/mantisbt fixed: 2.28.2 
Upgrade mantisbt/mantisbt to 2.28.2
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for mantisbt/mantisbt

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-44657, inspect your project dependencies for Mantisbt/mantisbt:

inspect dependencies for mantisbt/mantisbt

Analyze the terminal output to locate any version of Mantisbt/mantisbt in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.28.2), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. In Mantisbt/mantisbt, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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. ### Impact Cross-site scripting ### Patches - 26647b2e68ba30b9d7987d4e03d7a16416684bc2 ### Workarounds None ### Credits Thanks to siunam (Tang Cheuk Hei) for discovering and responsibly reporting the issue.

CVE-2026-44657 Affected Mantisbt/mantisbt Versions

1 component(s)
Fixed Versions:
2.28.2
Product / Package Ecosystem Affected Versions Fixed Version
mantisbt/mantisbt
 Packagist
< 2.28.2
2.28.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/mantisbt/mantisbt/security/advisories/GHSA-9c3j-xm6v-j7j3
GitHub Advisory / Wiki ADVISORY
https://github.com/mantisbt/mantisbt/security/advisories/GHSA-p6fr-rxq7-xcg8
NVD — CVE-2026-44657 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-44657
Security Fix Commit FIX COMMIT
https://github.com/mantisbt/mantisbt/commit/26647b2e68ba30b9d7987d4e03d7a16416684bc2
Mantisbt/mantisbt Source Repository REPOSITORY
https://github.com/mantisbt/mantisbt
mantisbt.org/bugs/view.php WEB
https://mantisbt.org/bugs/view.php?id=37020

Frequently Asked Questions

What is CVE-2026-44657?
CVE-2026-44657 is a security vulnerability in Mantisbt/mantisbt involving MantisBT Vulnerable to Stored XSS in File Download under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Mantisbt/mantisbt versions are affected?
Affected versions include releases prior to 2.28.2 across affected packages: mantisbt/mantisbt.
What version fixes CVE-2026-44657?
Upgrading to 2.28.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is mantisbt/mantisbt affected?
Yes, mantisbt/mantisbt is affected in releases prior to 2.28.2. Upgrade your dependency to 2.28.2 or later.
What CWE is associated with CVE-2026-44657?
CVE-2026-44657 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check Packagist dependencies for CVE-2026-44657?
Run the dependency tree command: 'inspect dependencies for mantisbt/mantisbt'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-p6fr-rxq7-xcg8",
  "modified" : "2026-06-09T10:24:02Z",
  "published" : "2026-05-11T19:40:43Z",
  "aliases" : [ "CVE-2026-44657" ],
  "summary" : "MantisBT Vulnerable to Stored XSS in File Download",
  "details" : "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.\n\n### Impact\nCross-site scripting\n\n### Patches\n- 26647b2e68ba30b9d7987d4e03d7a16416684bc2\n\n### Workarounds\nNone\n\n### Credits\nThanks to siunam (Tang Cheuk Hei) for discovering and responsibly reporting the issue.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "mantisbt/mantisbt"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.28.2"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.28.1"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/mantisbt/mantisbt/security/advisories/GHSA-9c3j-xm6v-j7j3"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mantisbt/mantisbt/security/advisories/GHSA-p6fr-rxq7-xcg8"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-44657"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mantisbt/mantisbt/commit/26647b2e68ba30b9d7987d4e03d7a16416684bc2"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mantisbt/mantisbt"
  }, {
    "type" : "WEB",
    "url" : "https://mantisbt.org/bugs/view.php?id=37020"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-11T19:40:43Z",
    "nvd_published_at" : "2026-05-28T21:16:31Z"
  }
}