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CVE-2021-21426

28
FAUCET Score

CVE-2021-21426 is a critical deserialization vulnerability affecting Magento-lts versions 19.4.12 and prior, and 20.0.8 and prior. This flaw, stemming from unsecured object deserialization, allows for unauthenticated, low-complexity attacks over the network, leading to complete compromise of confidentiality, integrity, and availability. While a patch exists in versions 19.4.13 and 20.0.9, there is currently no public exploit code available, and it is not listed on the CISA KEV catalog, indicating no active exploitation.

Impacted Technologies

VendorProductVersion(s)CPE
< 19.4.13CPE matchmatch criteria
cpe:2.3:a:openmage:magento:*:*:*:*:lts:*:*:*
>= 20.0.0, < 20.0.9CPE matchmatch criteria
cpe:2.3:a:openmage:magento:*:*:*:*:lts:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.20%
Probability of exploitation in next 30 days
EPSS Percentile
65.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0120 is in the 51st percentile among its peer group of 36,897 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 (2)

composerpatch availablevia ghsa
Product: openmage/magento-ltsFixed in: 19.4.13
composerpatch availablevia ghsa
Product: openmage/magento-ltsFixed in: 20.0.9

Vendor Advisories (1)

composerGHSA-m496-x567-f98ccritical

Fixes a bug in Zend Framework's Stream HTTP Wrapper

Apr 22, 2021

References

github.com / OpenMage/magento-lts/security/advisories/GHSA-m496-x567-f98c
Third Party Advisory