When running in debug mode and the debug-embed (off by default) feature is not enabled, the generated get method does not check that the input path is a child of the folder given.

This allows attackers to read arbitrary files in the file system if they have control over the filename given. The following code will print the contents of your /etc/passwd if adjusted with a correct number of ../s depending on where it is run from.

#[derive(rust_embed::RustEmbed)]
#[folder = "src/"]
pub struct Asset;

fn main() {
    let d = Asset::get("../../../etc/passwd").unwrap().data;
    println!("{}", String::from_utf8_lossy(&d));
}

The flaw was corrected by canonicalizing the input filename and ensuring that it starts with the canonicalized folder path.

Impact

When using tonic::transport::Server there is a remote DoS attack that can cause the server to exit cleanly on accepting a tcp/tls stream. This can be triggered via causing the accept call to error out with errors there were not covered correctly causing the accept loop to exit.

More information can be found here

Patches

Upgrading to tonic 0.12.3 and above contains the fix.

Workarounds

A custom accept loop is a possible workaround.

When a Some(...) value was passed to the properties argument of either of these functions, a use-after-free would result.

In practice this would nearly always result in OpenSSL treating the properties as an empty string (due to CString::drop's behavior).

The maintainers thank quitbug for reporting this vulnerability to us.

In the unique reclaim path of BytesMut::reserve, the condition

if v_capacity >= new_cap + offset

uses an unchecked addition. When new_cap + offset overflows usize in release builds, this condition may incorrectly pass, causing self.cap to be set to a value that exceeds the actual allocated capacity. Subsequent APIs such as spare_capacity_mut() then trust this corrupted cap value and may create out-of-bounds slices, leading to UB.

This behavior is observable in release builds (integer overflow wraps), whereas debug builds panic due to overflow checks.

PoC

use bytes::*;

fn main() {
    let mut a = BytesMut::from(&b"hello world"[..]);
    let mut b = a.split_off(5);

    // Ensure b becomes the unique owner of the backing storage
    drop(a);

    // Trigger overflow in new_cap + offset inside reserve
    b.reserve(usize::MAX - 6);

    // This call relies on the corrupted cap and may cause UB & HBO
    b.put_u8(b'h');
}

Workarounds

Users of BytesMut::reserve are only affected if integer overflow checks are configured to wrap. When integer overflow is configured to panic, this issue does not apply.