There is a potentially exploitable out of memory condition In Nanopb before 0.4.1, 0.3.9.5, and 0.2.9.4. When nanopb is compiled with PB_ENABLE_MALLOC, the message to be decoded contains a repeated string, bytes or message field and realloc() runs out of memory when expanding the array nanopb can end up calling free() on a pointer value that comes from uninitialized memory. Depending on platform this can result in a crash or further memory corruption, which may be exploitable in some cases. This problem is fixed in nanopb-0.4.1, nanopb-0.3.9.5, nanopb-0.2.9.4.

References

• GHSA-gcx3-7m76-287p
• https://nvd.nist.gov/vuln/detail/CVE-2020-5235
• nanopb/nanopb@45582f1
• nanopb/nanopb@7b39682
• nanopb/nanopb@aa9d0d1