CVE-2021-21426
Fixes a bug in Zend Framework's Stream HTTP Wrapper
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Fixes a bug in Zend Framework's Stream HTTP Wrapper
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.
- Record
CVE-2021-21426- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-502
- Updated
- 2026-11-02
EUVDEUVD-2021-0845
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.
- Record
EUVD-2021-0845- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-m496-x567-f98c
Fixes a bug in Zend Framework's Stream HTTP Wrapper
Impact
CVE-2021-3007: Backport of Zend_Http_Response_Stream, added certain type checking as a way to prevent exploitation. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-3007
This vulnerability is caused by the unsecured deserialization of an object. In versions higher than Zend Framework 3.0.0, the attacker abuses the Zend3 feature that loads classes from objects in order to upload and execute malicious code in the server. The code can be uploaded using the “callback” parameter, which in this case inserts a malicious code instead of the “callbackOptions” array.
Patches
Has the problem been patched? What versions should users upgrade to? v20.0.9 v19.4.13
- Record
GHSA-m496-x567-f98c- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-502
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2021-21426- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 7.5 High
AV:N/AC:L/Au:N/C:P/I:P/A:P - Weakness
- CWE-502
- Updated
- 2026-11-02
OSV
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.
- Record
CVE-2021-21426- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVGHSA-m496-x567-f98c
Fixes a bug in Zend Framework's Stream HTTP Wrapper
Impact
CVE-2021-3007: Backport of Zend_Http_Response_Stream, added certain type checking as a way to prevent exploitation. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-3007
This vulnerability is caused by the unsecured deserialization of an object. In versions higher than Zend Framework 3.0.0, the attacker abuses the Zend3 feature that loads classes from objects in order to upload and execute malicious code in the server. The code can be uploaded using the “callback” parameter, which in this case inserts a malicious code instead of the “callbackOptions” array.
Patches
Has the problem been patched? What versions should users upgrade to? v20.0.9 v19.4.13
- Record
GHSA-m496-x567-f98c- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-502
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
openmage/magento-ltsPackagist |
through 19.4.12 | 19.4.13 |
openmage/magento-ltsPackagist |
20.0.0 to 20.0.8 | 20.0.9 |
openmage/magento-ltsPackagist |
before 19.4.13, plus listed versions 1.9.1.11.9.2.01.9.2.11.9.2.21.9.2.3 Show 16 moreShow less1.9.2.41.9.3.01.9.3.1v19.4.0v19.4.1v19.4.10v19.4.11v19.4.12v19.4.2v19.4.3v19.4.4v19.4.5v19.4.6v19.4.7v19.4.8v19.4.9 |
19.4.13 |
openmage/magento-ltsPackagist |
20.0.0 up to 20.0.9, plus listed versions v20.0.0v20.0.1v20.0.2v20.0.3v20.0.4 Show 4 moreShow lessv20.0.5v20.0.6v20.0.7v20.0.8 |
20.0.9 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-21426 is a critical vulnerability (CVSS 9.8) in Openmage Magento, published April 21, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.20%, the 68th percentile. Fixed in openmage/magento-lts 19.4.13.