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MantisBT has an Authorization Bypass that Allows Uploading Attachments to Private Issues via REST API

Moderate severity GitHub Reviewed Published May 9, 2026 in mantisbt/mantisbt • Updated May 11, 2026

Package

composer mantisbt/mantisbt (Composer)

Affected versions

<= 2.28.1

Patched versions

2.28.2

Description

Impact

MantisBT allows an authenticated user to upload attachments to private Issues they are not authorized to access.

Patches

  • b262b4d2835b81394d75356dead66e52a6275206

Workarounds

None.

Credits

Thanks to Vishal Shukla for discovering and responsibly reporting the issue.

References

@dregad dregad published to mantisbt/mantisbt May 9, 2026
Published to the GitHub Advisory Database May 11, 2026
Reviewed May 11, 2026
Last updated May 11, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

EPSS score

Weaknesses

Improper Access Control

The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. Learn more on MITRE.

CVE ID

CVE-2026-34754

GHSA ID

GHSA-h4x5-gvx6-3rwc

Source code

Credits

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