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CVE-2021-43177

20
FAUCET Score

CVE-2021-43177 is a medium-severity vulnerability affecting tinfoilsecurity's devise-two-factor library prior to version 4.0.2. It allows an attacker to reuse a One-Time-Password (OTP) for a single immediately trailing interval due to an incomplete fix for a previous vulnerability. The attack requires low privileges and high attack complexity, but if successful, could lead to high confidentiality impact. There is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 4.0.2CPE matchmatch criteria
cpe:2.3:a:tinfoilsecurity:devise-two-factor:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.3MEDIUM

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
1.6
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.85%
Probability of exploitation in next 30 days
EPSS Percentile
54.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0085 is in the 43rd percentile among its peer group of 1,428 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

rubygemspatch availablevia ghsa
Product: devise-two-factorFixed in: 4.0.2

Vendor Advisories (1)

rubygemsGHSA-jm35-h8q2-73mpmedium

Improper one time password handling in devise-two-factor

Apr 7, 2022

References

github.com / tinfoil/devise-two-factor/security/advisories/GHSA-jm35-h8q2-73mp
Third Party Advisory