msgpack5: Truncated map32 headers throw an unexpected error
Impact
A truncated map32 header causes an out-of-bounds buffer read and throws RangeError instead of IncompleteBufferError. Applications that rely on IncompleteBufferError to wait for additional bytes may terminate a request, stream, or worker unexpectedly. No adjacent memory is disclosed because the buffer implementation checks bounds.
Patches
The decoder now validates the complete five-byte map32 header before reading its length and reports truncated input as IncompleteBufferError.
Workarounds
Require at least five bytes before decoding a value beginning with 0xdf, or catch RangeError and treat it as incomplete input only for truncated map32 headers.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | msgpack5 | >= 4.1.0, < 6.1.0 | 6.1.0 |
References
- https://github.com/mcollina/msgpack5/security/advisories/GHSA-8f34-f56x-9xph
- https://github.com/mcollina/msgpack5/commit/15443a1f2aa682a6aa37f1705ac628de5b866ad1
- https://github.com/mcollina/msgpack5
- https://github.com/mcollina/msgpack5/releases/tag/v6.1.0
- https://nvd.nist.gov/vuln/detail/CVE-2026-107302
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-125- Platform
- npm
- Package
msgpack5- Disclosed
- 08.10.2026
- Updated
- 19.10.2026 22:17
Sources and licenses
OSV / GitHub Advisory Database - GHSA-8f34-f56x-9xph - CC BY 4.0
Vulnerability history: msgpack5
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 8
- First → latest
- 03.2021 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 2
- Medium 5
- Low 1
Disclosures per year
- 2021: 1
- 2022: 0
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 7
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msgpack5: Truncated map32 headers throw an unexpected error this entry
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