CVE-2021-21401

Nanopb is a small code-size Protocol Buffers implementation in ansi C. In
Nanopb before versions 0.3.9.8 and 0.4.5, decoding a specifically formed
message can cause invalid free() or realloc() calls if the message type
contains an oneof field, and the oneof directly contains both a pointer
field and a non-pointer field. If the message data first contains the
non-pointer field and then the pointer field, the data of the non-pointer
field is incorrectly treated as if it was a pointer value. Such message
data rarely occurs in normal messages, but it is a concern when untrusted
data is parsed. This has been fixed in versions 0.3.9.8 and 0.4.5. See
referenced GitHub Security Advisory for more information including
workarounds.

Bugs

• <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=985844&gt;