What is CVE-2021-41078?

CVE-2021-41078 is a critical-severity insecure deserialization vulnerability in nameko (pip), affecting versions < 2.14.0. It is fixed in 2.14.0, 3.0.0rc10. Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect.

How severe is CVE-2021-41078?

CVE-2021-41078 has a CVSS score of 8.6 (Critical). 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 versions of nameko are affected by CVE-2021-41078?

nameko (pip) versions < 2.14.0 is affected.

Is there a fix for CVE-2021-41078?

Yes. CVE-2021-41078 is fixed in 2.14.0, 3.0.0rc10. Upgrade to this version or later.

Is CVE-2021-41078 exploitable, and should I be worried?

Whether CVE-2021-41078 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.

What actually determines whether CVE-2021-41078 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-2021-41078?

Upgrade: nameko to 2.14.0 or later, nameko to 3.0.0rc10 or later.

CVE-2021-41078 in nameko

Q: How severe is CVE-2021-41078?

CVE-2021-41078 has a CVSS score of 8.6 (Critical). 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.

Q: Which versions of nameko are affected by CVE-2021-41078?

nameko (pip) versions < 2.14.0 is affected.

Q: Is there a fix for CVE-2021-41078?

Yes. CVE-2021-41078 is fixed in 2.14.0, 3.0.0rc10. Upgrade to this version or later.

Q: Is CVE-2021-41078 exploitable, and should I be worried?

Whether CVE-2021-41078 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.

Q: What actually determines whether CVE-2021-41078 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.

Q: How do I fix CVE-2021-41078?

Upgrade: nameko to 2.14.0 or later, nameko to 3.0.0rc10 or later.

Summary

Nameko Arbitrary code execution due to YAML deserialization

Workarounds

The vulnerability is exploited by config files with malicious content. It can be avoided by only using config files that you trust.

Impact

Nameko can be tricked to perform arbitrary code execution when deserialising a YAML config file. Example:

# malicious.yaml
!!python/object/new:type
args: ['z', !!python/tuple [], {'extend': !!python/name:exec }]
listitems: "__import__('os').system('cat /etc/passwd')"

$ nameko run --config malicious.yaml test
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
...

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-2021-41078 has a CVSS score of 8.6 (Critical). The vector is requires local access, no privileges required, and user interaction required. 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 (2.14.0, 3.0.0rc10); upgrading removes the vulnerable code path.

Affected versions

nameko (< 2.14.0) nameko (>= 3.0.0rc0, <= 3.0.0rc9)

Security releases

nameko → 2.14.0 (pip) nameko → 3.0.0rc10 (pip)

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.

Already deployed Kodem?

See it in your environment New to Kodem? Get a demo →

Remediation advice

The problem was fixed in https://github.com/nameko/nameko/pull/722 and released in version 2.14.0, and in rc10 of the v3 pre-release.

Versions prior to 2.14.0, and v3.0.0rc0 through v3.0.0rc9 are still vulnerable.

Frequently Asked Questions

What is CVE-2021-41078? CVE-2021-41078 is a critical-severity insecure deserialization vulnerability in nameko (pip), affecting versions < 2.14.0. It is fixed in 2.14.0, 3.0.0rc10. Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect.
How severe is CVE-2021-41078? CVE-2021-41078 has a CVSS score of 8.6 (Critical). 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 versions of nameko are affected by CVE-2021-41078? nameko (pip) versions < 2.14.0 is affected.
Is there a fix for CVE-2021-41078? Yes. CVE-2021-41078 is fixed in 2.14.0, 3.0.0rc10. Upgrade to this version or later.
Is CVE-2021-41078 exploitable, and should I be worried? Whether CVE-2021-41078 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-2021-41078 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-2021-41078?
- Upgrade nameko to 2.14.0 or later
- Upgrade nameko to 3.0.0rc10 or later