No exploitation reportedFix available

CVE-2021-21426

Q: Is CVE-2021-21426 actively exploited?

Active exploitation of CVE-2021-21426 has not been confirmed. Its EPSS score was 1.2% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-21426?

CVE-2021-21426 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

No exploitation reported by the sources we read.

Published2021-04-21
Fixed in20.0.9 · 19.4.13
WeaknessCWE-502

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

Magento-lts is a long-term support alternative to Magento Community Edition (CE). In magento-lts versions 19.4.12 and prior and 20.0.8 and prior, there is a vulnerability caused by the unsecured deserialization of an object. A patch in versions 19.4.13 and 20.0.9 was back ported from Zend Framework 3. The vulnerability was assigned CVE-2021-3007 in Zend Framework.

Timeline

dates in UTC

2021-04-2121:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 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-2021-21426?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-21426?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Openmage magento

Branch	Affected	Fixed in	Source
20.0	≥ 20.0.0, < 20.0.9	20.0.9	NVD
19.4	< 19.4.13	19.4.13	NVD

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

Fix

Update Openmage magento to 20.0.9 · 19.4.13

Detection

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

Sources

CNACVSS 3.19.8read 2026-10-23
NVDCVSS 3.19.8read 2026-10-23
NVDCVSS 2.07.5read 2026-10-23
CNAweakness (CWE)CWE-502read 2026-10-23
FIRST EPSSEPSS score1.2 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published: 2021-04-21
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-21426?

Is CVE-2021-21426 actively exploited?

Active exploitation of CVE-2021-21426 has not been confirmed. Its EPSS score was 1.2% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-21426?

CVE-2021-21426 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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