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CVE-2021-21329

31
FAUCET Score

CVE-2021-21329 is a critical authentication bypass vulnerability affecting the RATCF open-source framework, which is used for hosting Capture the Flag events. This flaw allows users with multi-factor authentication (MFA) enabled to log in without providing a valid MFA token. With a CVSS score of 9.8, this vulnerability is easily exploitable over the network with no user interaction, leading to complete compromise of confidentiality, integrity, and availability. While there is no evidence of active exploitation, public exploit code, or inclusion in CISA's KEV catalog, the vulnerability has garnered significant community discussion, indicating awareness within the cybersecurity community.

Impacted Technologies

VendorProductVersion(s)CPE
< 2021-02-26CPE matchmatch criteria
cpe:2.3:a:ratcf:ratcf:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.7HIGH

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

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
2.2
Impact Score
5.8
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.46%
Probability of exploitation in next 30 days
EPSS Percentile
70.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0146 is in the 58th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

References

github.com / ractf/core/commit/c57a4d186bfc586ad3edfe4dcba9f11efbf22f09
PatchThird Party Advisory
github.com / ractf/core/commit/cebb67bd16a8296121201805332365ffccb29638
PatchThird Party Advisory
github.com / ractf/core/security/advisories/GHSA-fw57-f7mq-9q85
PatchThird Party Advisory