CVE-2026-47156
Fix: mantisbt/mantisbt@e3571c3CVE-2026-47156 is a Improper Authentication vulnerability in mantisbt/mantisbt. O3 Security confirms whether CVE-2026-47156 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
MantisBT: SOAP API Authentication Bypass with Privilege Escalation to Administrator
Real-World Exposure
mantisbt/mantisbtReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
MantisBT 2.28.3 and earlier contains 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.
Impact
- Full administrator access to the SOAP API from zero prior access (with self-registration enabled, which is the default)
- Read/write all issues including private issues and notes across all projects
- Full data exfiltration of all bug reports, attachments, user accounts (id, name, email), and non-private configuration values via the 71 SOAP operations available
- Destructive operations: delete projects, issues, attachments, tags, categories, and versions
- Data manipulation: create/modify issues, impersonate reporters, manage project structure
- Chains with other vulnerabilities: the SOAP admin access enables exploitation of SOAP vulnerabilities that require administrator privileges
Patches
Workarounds
None
Resources
Credits
MantisBT would like to thank McCaulay Hudson (@_McCaulay) of watchTowr for originally identifying and responsibly reporting the issue.
The vulnerability was subsequently discovered by other researchers, while the team was working on fixing and preparing the release. MantisBT credits them here, in chronological order of their reports:
- Keitaro Yamazaki (@tyage)
- Harrison Keating (@voraci0us)
- Chandler Johnson (@chndlrx)
- Bharat Devasani (@bharatdevasani)
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | mantisbt/mantisbt | all versions | 2.28.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mantisbt/mantisbt. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update mantisbt/mantisbt to 2.28.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-47156 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-47156 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-47156. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-47156 in your dependencies?
O3 detects CVE-2026-47156 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.