RUSTSEC-2026-0332
Vulnerability from osv_rustsec – Published: 2026-09-08 12:00 – Updated: 2026-10-07 14:40 – Source websiteWaveFormat::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.
{
"affected": [
{
"database_specific": {
"categories": [
"memory-exposure"
],
"cvss": null,
"informational": "unsound"
},
"ecosystem_specific": {
"affected_functions": null,
"affects": {
"arch": [],
"functions": [
"wasapi::WaveFormat::parse"
],
"os": [
"windows"
]
}
},
"package": {
"ecosystem": "crates.io",
"name": "wasapi",
"purl": "pkg:cargo/wasapi"
},
"ranges": [
{
"events": [
{
"introduced": "0.20.0"
},
{
"fixed": "0.25.0"
}
],
"type": "SEMVER"
}
],
"versions": []
}
],
"aliases": [],
"database_specific": {
"license": "CC0-1.0"
},
"details": "`WaveFormat::parse` is a safe function that takes a `\u0026WAVEFORMATEX`, which is\nonly valid for reads of `size_of::\u003cWAVEFORMATEX\u003e()` (18) bytes. When the header\nhas `wFormatTag == WAVE_FORMAT_EXTENSIBLE` and `cbSize \u003e= 22`, the function\nreinterprets the reference as a `WAVEFORMATEXTENSIBLE` and reads 40 bytes.\nNothing in the signature guarantees that the header sits at the start of a\nlarger buffer, so safe code can trigger an out-of-bounds read:\n\n```rust\nuse wasapi::WaveFormat;\nuse windows::Win32::Media::Audio::WAVEFORMATEX;\nuse windows::Win32::Media::KernelStreaming::WAVE_FORMAT_EXTENSIBLE;\n\nlet header = WAVEFORMATEX {\n wFormatTag: WAVE_FORMAT_EXTENSIBLE as u16,\n nChannels: 2,\n nSamplesPerSec: 48000,\n nAvgBytesPerSec: 384000,\n nBlockAlign: 8,\n wBitsPerSample: 32,\n cbSize: 22,\n};\n// Reads 22 bytes past the end of `header`.\nlet _ = WaveFormat::parse(\u0026header);\n```\n\nA more likely way to hit this is to copy the header out of a format pointer\nreturned by WASAPI (`let fmt = unsafe { *ptr };`) and pass `\u0026fmt`. The copy\nkeeps `cbSize`, but not the 22 bytes that follow it. The bytes read past the\nend are returned as the channel mask and subformat of the parsed format.\n\nThe flaw was corrected in commit `2562db7`, released in 0.25.0. `parse` is now\nan `unsafe fn` that takes a `*const WAVEFORMATEX`, and the caller must\nguarantee that the pointer is valid for reads of\n`size_of::\u003cWAVEFORMATEX\u003e() + cbSize` bytes. `WaveFormat::parse_from_blob_bytes`\n(available since 0.23.0) is the safe alternative and checks the slice length\nagainst `cbSize`.",
"id": "RUSTSEC-2026-0332",
"modified": "2026-10-07T14:40:27Z",
"published": "2026-09-08T12:00:00Z",
"references": [
{
"type": "PACKAGE",
"url": "https://crates.io/crates/wasapi"
},
{
"type": "ADVISORY",
"url": "https://rustsec.org/advisories/RUSTSEC-2026-0332.html"
},
{
"type": "REPORT",
"url": "https://github.com/HEnquist/wasapi-rs/issues/65"
},
{
"type": "WEB",
"url": "https://github.com/HEnquist/wasapi-rs/pull/64"
}
],
"related": [],
"severity": [],
"summary": "`WaveFormat::parse` reads past the end of a `\u0026WAVEFORMATEX`"
}
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