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GHSA-6p52-jr3q-c94g

HIGH

Nameko Arbitrary code execution due to YAML deserialization

Also known asCVE-2021-41078PYSEC-2021-383
Published
Oct 19, 2021
Updated
Mar 13, 2026
Affected
2 pkgs
Patched
2 / 2
Exploits
1 known

EPSS Exploitation Probability

via FIRST.org ↗
1.5%probability of exploitation in next 30 days
Lower Risk71th percentile+0.02%
0.97%1.31%1.65%1.99%1.5%1.5%Dec 25Apr 26Jun 26

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

2 pkgs affected
🐍nameko🐍nameko

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

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
... 

Patches

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.

Workarounds

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

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPInamekoall versions2.14.0
🐍PyPInameko3.0.0rc0&&< 3.0.0rc103.0.0rc10
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nameko. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update nameko to 2.14.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-6p52-jr3q-c94g is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether GHSA-6p52-jr3q-c94g is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-6p52-jr3q-c94g. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Impact Nameko can be tricked to perform arbitrary code execution when deserialising a YAML config file. Example: ``` yaml # malicious.yaml !!python/object/new:type args: ['z', !!python/tuple [], {'extend': !!python/name:exec }] listitems: "__import__('os').system('cat /etc/passwd')" ``` ``` shell $ 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 ... ``` ### Pa
O3 Security · Impact-Aware SCA

Is GHSA-6p52-jr3q-c94g in your dependencies?

O3 detects GHSA-6p52-jr3q-c94g across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.