CVE-2026-40597: Mantisbt/mantisbt MantisBT Has A Content Security Vulnerability

HIGH
Advisory Identifier: GHSA-9c3j-xm6v-j7j3
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CWE-358 CWE-79
Published
Advisory Summary

CVE-2026-40597 is a HIGH mantisbt has a content security vulnerability (CWE-358: Improperly Implemented Security Check for Standard) affecting Mantisbt/mantisbt libraries in the Packagist ecosystem. The issue involves mantisbt has a content security policy bypass via attachments. Remediation is available by upgrading affected packages to version 2.28.2.

CVE-2026-40597 at a Glance

CVE Identifier CVE-2026-40597
GHSA Identifier GHSA-9c3j-xm6v-j7j3
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-358: Improperly Implemented Security Check for Standard
Affected Product Mantisbt/mantisbt
Package Ecosystem Packagist
Published Date
Last Updated

How to Fix CVE-2026-40597

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-2026-40597, 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-358: Improperly Implemented Security Check for Standard, where the product does not implement or incorrectly implements one or more security-relevant checks as specified by the design of a standardized algorithm, protocol, or technique. 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

Given any pre-existing XSS / HTML injection vulnerability, an attacker can bypass the Content Security Policy's _script-src_ directive by uploading a crafted attachment to any issue that, when accessed via the _file_download.php_ link, will be downloaded with a valid JavaScript MIME type resulting in script execution. The uploaded payload must be sniffed as a valid JavaScript MIME type by PHP finfo (see file_create_finfo() API function). Non-JavaScript MIME types will not get imported in a `<script>` tag by the browser, due to response header X-Content-Type-Options being set to _nosniff_, which requires all imported JavaScript files to be a valid JavaScript MIME type. ### Impact Cross-site scripting ### Patches - 9e3bee2e7b909f4e3596985892b8bc8bee9e0bfe ### Workarounds None ### Credits Thanks to siunam (Tang Cheuk Hei) for discovering and responsibly reporting the issue.

CVE-2026-40597 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
NVD — CVE-2026-40597 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-40597
Security Fix Commit FIX COMMIT
https://github.com/mantisbt/mantisbt/commit/9e3bee2e7b909f4e3596985892b8bc8bee9e0bfe
Mantisbt/mantisbt Source Repository REPOSITORY
https://github.com/mantisbt/mantisbt
mantisbt.org/bugs/view.php WEB
https://mantisbt.org/bugs/view.php?id=37016

Frequently Asked Questions

What is CVE-2026-40597?
CVE-2026-40597 is a security vulnerability in Mantisbt/mantisbt involving MantisBT has a Content Security Policy bypass via attachments under CWE-358: Improperly Implemented Security Check for Standard.
Which Mantisbt/mantisbt versions are affected?
Affected versions include releases prior to 2.28.2 across affected packages: mantisbt/mantisbt.
What version fixes CVE-2026-40597?
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-2026-40597?
CVE-2026-40597 is classified under CWE-358: Improperly Implemented Security Check for Standard (The product does not implement or incorrectly implements one or more security-relevant checks as specified by the design of a standardized algorithm, protocol, or technique.).
How can I check Packagist dependencies for CVE-2026-40597?
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-9c3j-xm6v-j7j3",
  "modified" : "2026-06-08T23:20:21Z",
  "published" : "2026-05-11T19:34:48Z",
  "aliases" : [ "CVE-2026-40597" ],
  "summary" : "MantisBT has a Content Security Policy bypass via attachments",
  "details" : "Given any pre-existing XSS / HTML injection vulnerability, an attacker can bypass the Content Security Policy's _script-src_ directive by uploading a crafted attachment to any issue that, when accessed via the _file_download.php_ link, will be downloaded with a valid JavaScript MIME type resulting in script execution.\n\nThe uploaded payload must be sniffed as a valid JavaScript MIME type by PHP finfo (see file_create_finfo() API function). Non-JavaScript MIME types will not get imported in a `<script>` tag by the browser, due to response header X-Content-Type-Options being set to _nosniff_, which requires all imported JavaScript files to be a valid JavaScript MIME type.\n\n### Impact\nCross-site scripting\n\n### Patches\n- 9e3bee2e7b909f4e3596985892b8bc8bee9e0bfe\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:N/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" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-40597"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mantisbt/mantisbt/commit/9e3bee2e7b909f4e3596985892b8bc8bee9e0bfe"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mantisbt/mantisbt"
  }, {
    "type" : "WEB",
    "url" : "https://mantisbt.org/bugs/view.php?id=37016"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-358", "CWE-79" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-11T19:34:48Z",
    "nvd_published_at" : "2026-05-22T20:16:34Z"
  }
}