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MEDIUM severity

CVE-2021-43177 — devise-two-factor

MEDIUM

CVE-2021-43177 is a medium-severity (CVSS 5.3) CWE-254 vulnerability in devise-two-factor. A fix is available for devise-two-factor — see the affected versions and patch details below.

Improper one time password handling in devise-two-factor

Also known asGHSA-jm35-h8q2-73mp
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.9%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs60th percentile — riskier than 60% of all scored CVEsHighest risk
0.00%0.46%0.92%1.38%0.4%0.9%May 26Sep 26Nov 26

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

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
💎devise-two-factor

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.

Description

Impact

As a result of an incomplete fix for CVE-2015-7225, in versions of devise-two-factor prior to 4.0.2 it is possible to reuse a One-Time-Password (OTP) for one (and only one) immediately trailing interval.

Patches

This vulnerability has been patched in version 4.0.2 which was released on March 24th, 2022. Individuals using this package are strongly encouraged to upgrade as soon as possible.

Credit for discovery

Benoit Côté-Jodoin Michael Nipper - https://github.com/tinfoil/devise-two-factor/issues/106

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
💎RubyGemsdevise-two-factorall versions4.0.2bundle update devise-two-factor --conservative

Affected Products

1 product · 1 configurations
Application
devise-two-factortinfoilsecurity
< 4.0.2
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update devise-two-factor to 4.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-43177 is resolved across your whole dependency graph.

  3. 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.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

UbuntuMEDIUM
USN-7050-1Ubuntu

Frequently Asked Questions

### Impact As a result of an incomplete fix for CVE-2015-7225, in versions of devise-two-factor prior to 4.0.2 it is possible to reuse a One-Time-Password (OTP) for one (and only one) immediately trailing interval. ### Patches This vulnerability has been patched in version 4.0.2 which was released on March 24th, 2022. Individuals using this package are strongly encouraged to upgrade as soon as possible. ### Credit for discovery Benoit Côté-Jodoin Michael Nipper - https://github.com/tinfoil/devise-two-factor/issues/106
O3 Security · Impact-Aware SCA

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CVE-2021-43177: devise-two-factor — Fixed in 4.0.2