Summary
Phar unserialization vulnerability in phpMussel
Workarounds
Is there a way for users to fix or remediate the vulnerability without upgrading?
Yes. In the package's configuration, disable archive checking by setting check_archives to false (thus avoiding execution of the affected parts of the codebase entirely).
References
Are there any links users can visit to find out more?
Yes. The vulnerability is documented at SECURITY.md and also at #167.
For more information
If you have any questions or comments about this advisory:
- Comment at the issue linked to this advisory, or..
- Contact the package author.
Impact
What kind of vulnerability is it? Who is impacted?
Anyone using >= v1.0.0 < v1.6.0.
Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect. Typical impact: arbitrary code execution or logic abuse.
CVE-2020-4043 has a CVSS score of 7.7 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.6.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Has the problem been patched? What versions should users upgrade to?
Yes. Upgrading to at least >= v1.6.0 (the earliest safe version) will resolve the problem. However, as multiple new major versions have been released since that version, upgrading to the latest available version is recommended, in order to protect against any potential future vulnerabilities, unknown at the time of writing this advisory.
Frequently Asked Questions
- What is CVE-2020-4043? CVE-2020-4043 is a high-severity insecure deserialization vulnerability in phpmussel/phpmussel (composer), affecting versions >= 1.0.0, < 1.6.0. It is fixed in 1.6.0. Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect.
- How severe is CVE-2020-4043? CVE-2020-4043 has a CVSS score of 7.7 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which packages are affected by CVE-2020-4043?
phpmussel/phpmussel(composer) (versions >= 1.0.0, < 1.6.0)Maikuolan/phpMussel(composer) (versions >= 1.0.0, < 1.6.0)
- Is there a fix for CVE-2020-4043? Yes. CVE-2020-4043 is fixed in 1.6.0. Upgrade to this version or later.
- Is CVE-2020-4043 exploitable, and should I be worried? Whether CVE-2020-4043 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2020-4043 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2020-4043?
- Upgrade
phpmussel/phpmusselto 1.6.0 or later - Upgrade
Maikuolan/phpMusselto 1.6.0 or later
- Upgrade