Executive brief
MantisBT, a popular open-source bug tracking system, contains a critical flaw in its SOAP API that allows unauthorized users to gain full administrator access. By exploiting this vulnerability, an attacker can read, modify, or delete all bug reports, private notes, and user data. In default installations where self-registration is enabled, even a newly registered user can impersonate any other account, including administrators, leading to total data exposure and potential service disruption.
Technical details
A critical authentication bypass (CWE-287/CWE-639) exists in MantisBT versions 2.28.3 and earlier within the SOAP API's mci_check_login() function. The vulnerability arises because the SOAP API allows a client to provide both a username and a cookie string, but fails to verify that the cookie actually belongs to the provided username. An attacker with a valid MANTIS_STRING_COOKIE (obtainable via default self-registration) can supply their own cookie alongside the 'administrator' username to gain full administrative privileges. This attack is reachable over the network without prior valid credentials if self-registration is enabled. The REST API and Web UI are not affected as they derive the username server-side from the session or token. A patch is available in version 2.28.4.
Affected products
- MantisBT MantisBT <= 2.28.3
Timeline
- 2026-07-15: advisory
- 2026-07-15: disclosed
- 2026-07-15: patched