MantisBT: SOAP API Authentication Bypass with Privilege Escalation to Administrator

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

9.3 · 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 · score source

EPSS

• CVE-2026-47156: 0.69% estimated exploitation activity in the next 30 days; percentile 52.69 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

MantisBT 2.28.3 and earlier contains a critical authentication bypass in the SOAP API's mcichecklogin() function. Any user knowing any valid cookiestring 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 ($gallowsignup = ON). A self-registered user can use their own cookiestring (readable from their browser's MANTISSTRINGCOOKIE 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 MANTISSTRINGCOOKIE against the logged-in user through authiscookievalid(). The username is derived…

Published by the source

15 Jul 2026, 16:45 UTC

Last modified by the source

16 Jul 2026, 00:03 UTC

Source last checked

26 Oct 2026, 14:50 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-c2xg-qjqw-2v98

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# Patch Next advisory brief: CVE-2026-47156

Advisory: MantisBT: SOAP API Authentication Bypass with Privilege Escalation to Administrator
IDs: CVE-2026-47156, GHSA-c2xg-qjqw-2v98
Record: https://patchnext.com/advisories/cve-2026-47156 (revision 1, source checked 26 Oct 2026, 14:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: mantisbt/mantisbt 2.28.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist mantisbt/mantisbt: affected <= 2.28.3; fixed in 2.28.4

## Suggested inspection (read-only)
- Packagist mantisbt/mantisbt: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on mantisbt/mantisbt.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-c2xg-qjqw-2v98 (GitHub-reviewed advisory GHSA-c2xg-qjqw-2v98 lists affected ranges: Packagist mantisbt/mantisbt >=0 <=2.28.3)

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