No exploitation reportedFix available

CVE-2021-23127

Q: Is CVE-2021-23127 actively exploited?

Active exploitation of CVE-2021-23127 has not been confirmed. Its EPSS score was 1.4% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-23127?

CVE-2021-23127 has a CVSS v3 base score of 9.1 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

No exploitation reported by the sources we read.

Published2021-03-04
Fixed in3.9.25

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

An issue was discovered in Joomla! 3.2.0 through 3.9.24. Usage of an insufficient length for the 2FA secret accoring to RFC 4226 of 10 bytes vs 20 bytes.

Timeline

dates in UTC

2021-03-0418:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-23127?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-23127?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV

Joomla

Branch	Affected	Fixed in	Source
3.x	≥ 3.2.0, < 3.9.25	3.9.25	NVD · OSV

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Joomla to 3.9.25

Advisories and patches

developer.joomla.orgVendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.19.1read 2026-10-23
NVDCVSS 2.06.4read 2026-10-23
FIRST EPSSEPSS score1.4 %2026-10-23
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Published: 2021-03-04
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-23127?

An issue was discovered in Joomla! 3.2.0 through 3.9.24. Usage of an insufficient length for the 2FA secret accoring to RFC 4226 of 10 bytes vs 20 bytes.

Is CVE-2021-23127 actively exploited?

Active exploitation of CVE-2021-23127 has not been confirmed. Its EPSS score was 1.4% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-23127?

CVE-2021-23127 has a CVSS v3 base score of 9.1 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

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