RUSTSEC-2026-0332 `WaveFormat::parse` reads past the end of a `&WAVEFORMATEX`

Not scored Published

A Rust library allows out-of-bounds memory reads when parsing specific audio format headers, potentially leaking sensitive data.

Exploited in the wild
Not known
Login needed
Not needed
Attackable
Not stated
Victim action needed
Not needed
Fix
Available

What is RUSTSEC-2026-0332?

RUSTSEC-2026-0332 is a memory corruption vulnerability in wasapi, published on 8 Sep 2026.

Official description

WaveFormat::parse is a safe function that takes a &WAVEFORMATEX, which is only valid for reads of size_of::<WAVEFORMATEX>() (18) bytes. When the header has wFormatTag == WAVE_FORMAT_EXTENSIBLE and cbSize >= 22, the function reinterprets the reference as a WAVEFORMATEXTENSIBLE and reads 40 bytes. Nothing in the signature guarantees that the header sits at the start of a larger buffer, so safe code can trigger an out-of-bounds read:

use wasapi::WaveFormat;
use windows::Win32::Media::Audio::WAVEFORMATEX;
use windows::Win32::Media::KernelStreaming::WAVE_FORMAT_EXTENSIBLE;

let header = WAVEFORMATEX {
    wFormatTag: WAVE_FORMAT_EXTENSIBLE as u16,
    nChannels: 2,
    nSamplesPerSec: 48000,
    nAvgBytesPerSec: 384000,
    nBlockAlign: 8,
    wBitsPerSample: 32,
    cbSize: 22,
};
// Reads 22 bytes past the end of `header`.
let _ = WaveFormat::parse(&header);

A more likely way to hit this is to copy the header out of a format pointer returned by WASAPI (let fmt = unsafe { *ptr };) and pass &fmt. The copy keeps cbSize, but not the 22 bytes that follow it. The bytes read past the end are returned as the channel mask and subformat of the parsed format.

The flaw was corrected in commit 2562db7, released in 0.25.0. parse is now an unsafe fn that takes a *const WAVEFORMATEX, and the caller must guarantee that the pointer is valid for reads of size_of::<WAVEFORMATEX>() + cbSize bytes. WaveFormat::parse_from_blob_bytes (available since 0.23.0) is the safe alternative and checks the slice length against cbSize.

Which versions are affected by RUSTSEC-2026-0332?

1 open source package ship an affected version, including wasapi.

PackageAffectedFixed in
wasapi crates.ioFrom 0.20.00.25.0

How do I fix RUSTSEC-2026-0332?

Upgrade wasapi to 0.25.0 or later.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is RUSTSEC-2026-0332 being exploited?

There is no known exploitation of RUSTSEC-2026-0332 in the wild and no public exploit code.

Sources

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