How severe is CVE-2021-21426?

CVE-2021-21426 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-21426 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (65th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21426?

CVE-2021-21426 affects Openmage Magento. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-21426?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-21426 published?

CVE-2021-21426 was published on 2021-04-21 and last updated on 2026-06-17.

CVE-2021-21426

CVE-2021-21426 is a critical-severity vulnerability in Openmage Magento with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-502.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 1% (65th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-502
Affected product: Openmage Magento
Published: 2021-04-21
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-21426?: 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.
How severe is CVE-2021-21426?: CVE-2021-21426 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-21426 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (65th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21426?: CVE-2021-21426 affects Openmage Magento. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-21426?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-21426 published?: CVE-2021-21426 was published on 2021-04-21 and last updated on 2026-06-17.

References

https://github.com/OpenMage/magento-lts/security/advisories/GHSA-m496-x567-f98c

Affected products (1)

cpe:2.3:a:openmage:magento:*:*:*:*:lts:*:*:*

More vulnerabilities in Openmage Magento

CVE-2021-21427 — Critical (CVSS 9.1): Magento-lts is a long-term support alternative to Magento Community Edition (CE). A vulnerability in magento-lts…
CVE-2026-40488 — High (CVSS 8.8): Magento Long Term Support (LTS) is an unofficial, community-driven project provides an alternative to the Magento…
CVE-2021-41144 — High (CVSS 8.8): OpenMage LTS is an e-commerce platform. Prior to versions 19.4.22 and 20.0.19, a layout block was able to bypass the…
CVE-2026-25524 — High (CVSS 8.1): Magento Long Term Support (LTS) is an unofficial, community-driven project provides an alternative to the Magento…
CVE-2020-15244 — High (CVSS 8.0): In Magento (rubygems openmage/magento-lts package) before versions 19.4.8 and 20.0.4, an admin user can generate soap…
CVE-2023-41879 — High (CVSS 7.5): Magento LTS is the official OpenMage LTS codebase. Guest orders may be viewed without authentication using a…

All CVEs affecting Openmage Magento →

Other CWE-502 (Deserialization of Untrusted Data) vulnerabilities

CVE-2026-41104 — Critical (CVSS 10.0): Deserialization of untrusted data in Microsoft Planetary Computer Pro allows an unauthorized attacker to disclose…
CVE-2026-43633 — Critical (CVSS 10.0): HestiaCP versions 1.9.0 through 1.9.4 contain a deserialization vulnerability in the web terminal component caused by a…
CVE-2026-33819 — Critical (CVSS 10.0): Deserialization of untrusted data in Microsoft Bing allows an unauthorized attacker to execute code over a network.
CVE-2026-20131 — Critical (CVSS 10.0): A vulnerability in the web-based management interface of Cisco Secure Firewall Management Center (FMC) Software could…
CVE-2026-25632 — Critical (CVSS 10.0): EPyT-Flow is a Python package designed for the easy generation of hydraulic and water quality scenario data of water…
CVE-2025-14931 — Critical (CVSS 10.0): Hugging Face smolagents Remote Python Executor Deserialization of Untrusted Data Remote Code Execution Vulnerability.…

Browse all CWE-502 (Deserialization of Untrusted Data) vulnerabilities →