How severe is CVE-2026-55186?

CVE-2026-55186 has a CVSS score of 4.2/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-55186?

CVE-2026-55186 affects the following packages: silverstripe/mfa (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2026-55186?

Update silverstripe/mfa to 6.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-55186 is resolved across your whole dependency graph.

How do I detect CVE-2026-55186 in my Packagist dependencies?

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

How do I mitigate CVE-2026-55186 if there is no patch (or I can't update yet)?

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.

Is CVE-2026-55186 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-55186 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.

When was CVE-2026-55186 published, and has it been updated?

CVE-2026-55186 was published on October 29, 2026 and was last updated on October 29, 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

MEDIUM severity

CVE-2026-55186 — mfa

MEDIUM

CVE-2026-55186 is a medium-severity (CVSS 4.2) vulnerability in silverstripe/mfa. A fix is available for silverstripe/mfa — see the affected versions and patch details below.

MultiFactor Authentication for SilverStripe can bypass MFA during password reset flow

Published

Oct 29, 2026

Updated

Oct 29, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 29, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

🐘silverstripe/mfa

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

Impact

In CMS 5, the password reset flow let a user with multi-factor authentication enabled change their password and get a logged-in session before completing multi-factor authentication. Exploiting this requires access to the user's email account. CMS 6 is not affected.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`silverstripe/mfa`	all versions	6.0.0`composer require silverstripe/mfa:^6.0.0`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for silverstripe/mfa, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update silverstripe/mfa to 6.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-55186 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.

Frequently Asked Questions

### Impact In CMS 5, the password reset flow let a user with multi-factor authentication enabled change their password and get a logged-in session before completing multi-factor authentication. Exploiting this requires access to the user's email account. CMS 6 is not affected.

O3 Security · Impact-Aware SCA

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