MantisBT is an open source bug tracker. Versions 2.28.3 and earlier contain a critical authentication bypass in the SOAP API's mci_check_login() function. Any user knowing any valid cookie_string can authenticate as any other user (knowing their username), including the administrator, without knowing the target's password. The vulnerability is exploitable with zero prior access on default MantisBT installations because self-registration is enabled by default ($g_allow_signup = ON). A self-registered user can use their own cookie_string (readable from their browser's MANTIS_STRING_COOKIE cookie after login) to impersonate the administrator via the SOAP API. The REST API is NOT affected. The REST API's AuthMiddleware derives the username server-side from the API token or session cookie, so the username cannot be spoofed. The Web UI is NOT affected. The Web UI authenticates via PHP session cookies (PHPSESSID) and validates the MANTIS_STRING_COOKIE against the logged-in user through auth_is_cookie_valid(). The username is derived server-side from the cookie, not supplied by the client. Version 2.28.4 contains a patch. No known workarounds are available.

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-c2xg-qjqw-2v98 MantisBT: SOAP API Authentication Bypass with Privilege Escalation to Administrator
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Wed, 09 Sep 2026 16:30:00 +0000

Type Values Removed Values Added
Description MantisBT is an open source bug tracker. Versions 2.28.3 and earlier contain a critical authentication bypass in the SOAP API's mci_check_login() function. Any user knowing any valid cookie_string can authenticate as any other user (knowing their username), including the administrator, without knowing the target's password. The vulnerability is exploitable with zero prior access on default MantisBT installations because self-registration is enabled by default ($g_allow_signup = ON). A self-registered user can use their own cookie_string (readable from their browser's MANTIS_STRING_COOKIE cookie after login) to impersonate the administrator via the SOAP API. The REST API is NOT affected. The REST API's AuthMiddleware derives the username server-side from the API token or session cookie, so the username cannot be spoofed. The Web UI is NOT affected. The Web UI authenticates via PHP session cookies (PHPSESSID) and validates the MANTIS_STRING_COOKIE against the logged-in user through auth_is_cookie_valid(). The username is derived server-side from the cookie, not supplied by the client. Version 2.28.4 contains a patch. No known workarounds are available.
Title MantisBT: SOAP API Authentication Bypass with Privilege Escalation to Administrator
Weaknesses CWE-287
CWE-639
References
Metrics cvssV4_0

{'score': 9.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-09-09T16:06:40.283Z

Reserved: 2026-05-18T21:25:34.496Z

Link: CVE-2026-47156

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-09T17:17:21.833

Modified: 2026-09-09T17:17:21.833

Link: CVE-2026-47156

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-09T18:15:13Z

Weaknesses