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RUSTSEC-2020-0009

read_scalar and read_scalar_at allow transmuting values without unsafe blocks

Issued
Package
flatbuffers (crates.io)
Type
Vulnerability
Aliases
Details
https://github.com/google/flatbuffers/issues/5825
CVSS Score
7.5 HIGH
CVSS Details
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Patched
  • >=2.0.0
Unaffected
  • <0.4.0
Affected Functions
Version
flatbuffers::read_scalar
  • >=0.4.0
flatbuffers::read_scalar_at
  • >=0.4.0

Description

The read_scalar and read_scalar_at functions are unsound because they allow transmuting values without unsafe blocks.

The following example shows how to create a dangling reference:

fn main() {
    #[derive(Copy, Clone, PartialEq, Debug)]
    struct S(&'static str);
    impl flatbuffers::EndianScalar for S {
        fn to_little_endian(self) -> Self { self }
        fn from_little_endian(self) -> Self { self }
    }
    println!("{:?}", flatbuffers::read_scalar::<S>(&[1; std::mem::size_of::<S>()]));
}