CVE-2021-21426Network attack vector

Remote code execution via stream-name object coercion

Published Apr 21, 2021 · Updated Aug 3, 2024

Object deserialization in OpenMage LTS 19.4.12 and earlier and 20.0.8 and earlier allows remote attackers to execute code. Zend_Http_Response_Stream::__destruct passes a deserialized object in streamName to unlink(), implicitly invoking its __toString method. Exploitation requires an application path that unserializes attacker-controlled data into the stream response object; successful gadget chaining executes code on the server.

CVSS severity9.8
Critical
EPSS probability1.20%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Object deserialization in OpenMage LTS 19.4.12 and earlier and 20.0.8 and earlier allows remote attackers to execute code. Zend_Http_Response_Stream::__destruct passes a deserialized object in streamName to unlink(), implicitly invoking its __toString method. Exploitation requires an application path that unserializes attacker-controlled data into the stream response object; successful gadget chaining executes code on the server.

The record

CVE
CVE-2021-21426
Published
Apr 21, 2021
Updated
Aug 3, 2024
Vendor
OpenMage
Product
OpenMage LTS
Classifications
CWE-502, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 21, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=<= 19.4.12
  2. Affected versionversion=<= 20.0.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OpenMage · OpenMage LTSversion=<= 19.4.12; version=<= 20.0.8

Published CVSS scores

7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 11, 2026Sep 17, 2026
Latest reporting daySep 17, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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