GHSA-qjxf-mc72-wjr2 is a medium-severity (CVSS 5.3) CWE-331 vulnerability in devise-two-factor. A fix is available for devise-two-factor — see the affected versions and patch details below.
Devise-Two-Factor Authentication Uses Insufficient Default OTP Shared Secret Length
Exploitation Status
No confirmed exploitation observed yet
- 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 GHSA-qjxf-mc72-wjr2.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-qjxf-mc72-wjr2 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,238 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
devise-two-factor💎devise-two-factorReal-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
Summary
Under the default configuration, Devise-Two-Factor versions 1.0.0 or >= 4.0.0 & < 6.0.0 generate TOTP shared secrets that are 120 bits instead of the 128-bit minimum defined by RFC 4226. Using a shared secret shorter than the minimum to generate a multi-factor authentication code could make it easier for an attacker to guess the shared secret and generate valid TOTP codes.
Remediation
Devise-Two-Factor should be upgraded to version v6.0.0 as soon as possible. After upgrading, the length of shared secrets and TOTP URLs generated by the library will increase since the new shared secrets will be longer.
If upgrading is not possible, you can override the default otp_secret_length attribute in the model when configuring two_factor_authenticable and set it to a value of at least 26 to ensure newly generated shared secrets are at least 128-bits long.
After upgrading or implementing the workaround, applications using Devise-Two-Factor may wish to migrate users to the new OTP length to provide increased protection for those accounts. Turning off OTP for users by setting otp_required_for_login to false is not recommended since it would leave accounts unprotected. However, you may wish to implement application logic that checks the length of a user's shared secret and prompts users to re-enroll in OTP.
Background
Devise-Two-Factor uses ROTP to generate shared secrets for TOTP. In ROTP < 5.0.0, the first argument to the ROTP::Base32#random_base32 function represented the number of bytes to read from SecureRandom which were then returned as a base32-encoded string. In ROTP 5.1.0, this function was changed so that the first argument now represents the length of the base32-encoded string returned by the function instead of the number of bytes to read from SecureRandom resulting in a shorter key being generated for the same input value. (https://github.com/mdp/rotp/commit/15d5104e3cb99f97d36c772f8f09cf7e2e77de20).
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | devise-two-factor | ≥ 4.0.0&&< 6.0.0 | 6.0.0bundle update devise-two-factor --conservative |
| 💎RubyGems | devise-two-factor | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
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.
Fix
Update devise-two-factor to 6.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-qjxf-mc72-wjr2 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-qjxf-mc72-wjr2 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-qjxf-mc72-wjr2. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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.
Frequently Asked Questions
Is GHSA-qjxf-mc72-wjr2 in your dependencies?
O3 Security finds GHSA-qjxf-mc72-wjr2 across RubyGems dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.