GHSA-85rr-4rh9-hhwh Memory leak in Nanopb

• PyPI nanopb: >= 0.3.2, < 0.3.9.7 → fixed in 0.3.9.7 • PyPI nanopb: >= 0.4.0, < 0.4.4 → fixed in 0.4.4

Impact Decoding specifically formed message can leak memory if dynamic allocation is enabled and an oneof field contains a static submessage that contains a dynamic field, and the message being decoded contains the submessage multiple times. This is rare in normal messages, but it is a concern when untrusted data is parsed. Patches Preliminary patch is available on git and problem will be patched in versions 0.3.9.7 and 0.4.4 once testing has been completed. Workarounds Following workarounds are available: • Set the option `no_unions` for the oneof field. This will generate fields as separate instead of C union, and avoids triggering the problematic code. • Set the type of the submessage field inside oneof to `FT_POINTER`. This way the whole submessage will be dynamically allocated and the problematic code is not executed. • Use an arena allocator for nanopb, to make sure all memory can be released afterwards. References Bug report: https://github.com/nanopb/nanopb/issues/615 For more information If you have any questions or comments about this advisory, comment on the bug report linked above.