How severe is CVE-2026-47156?

No CVSS score has been assigned to CVE-2026-47156 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-47156?

CVE-2026-47156 affects the following packages: mantisbt/mantisbt (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2026-47156?

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.

How do I detect CVE-2026-47156 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mantisbt/mantisbt, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-47156 if there is no patch (or I can't update yet)?

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Is CVE-2026-47156 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-47156 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-47156?

CVE-2026-47156 has an EPSS (Exploit Prediction Scoring System) score of 0.7%, placing it in the 52th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-47156?

CVE-2026-47156 is classified as Improper Authentication (CWE-287), CWE-639 (CWE-639). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-47156 published, and has it been updated?

CVE-2026-47156 was published on September 9, 2026 and was last updated on October 21, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘 Packagist

Not in CISA KEV

CVE-2026-47156 — mantisbt

Fix: mantisbt/mantisbt@e3571c3

CVE-2026-47156 is a Improper Authentication vulnerability in mantisbt/mantisbt. A fix is available for mantisbt/mantisbt — see the affected versions and patch details below.

MantisBT: SOAP API Authentication Bypass with Privilege Escalation to Administrator

Also known asGHSA-c2xg-qjqw-2v98

Published

Sep 9, 2026

Updated

Oct 21, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 23, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
A successful exploit gives an attacker total control of the affected component, not partial access.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-47156.

EPSS Exploitation Probability

via FIRST.org ↗

0.7%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs52th percentile — riskier than 52% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

🐘mantisbt/mantisbt

Real-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

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

https://github.com/mantisbt/mantisbt/commit/e3571c319b1721b41b0dc4b5b5203cbdcbe0c2ee

Workarounds

None

Resources

https://mantisbt.org/bugs/view.php?id=37121

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

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`mantisbt/mantisbt`	all versions	2.28.4`composer require mantisbt/mantisbt:^2.28.4`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mantisbt/mantisbt, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

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 admin

O3 Security · Impact-Aware SCA

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