Vulnerability · Published Oct 8, 2026 · Assigned by GitHub_M
CVE-2026-107302msgpack5: Truncated map32 headers throw an unexpected error
High 7.5
In plain English
A high-severity out-of-bounds read in msgpack5 from mcollina. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the decoder reads the four-byte length of a map32 value before validating that the complete five-byte header is available. A truncated map32 header therefore causes a checked out-of-bounds buffer read and throws RangeError instead of IncompleteBufferError, which can unexpectedly terminate a request, stream, or worker in applications that wait for additional bytes after IncompleteBufferError. There is no adjacent-memory disclosure because the buffer implementation checks bounds. This issue is fixed in version 6.1.0.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | msgpack5 | 6.1.0 | GHSA-8f34-f56x-9xph |
Affected products (as reported)
Weakness: CWE-125 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- https://github.com/mcollina/msgpack5/security/advisories/GHSA-8f34-f56x-9xph x_refsource_CONFIRM
- https://github.com/mcollina/msgpack5/commit/15443a1f2aa682a6aa37f1705ac628de5b866ad1 x_refsource_MISC
- https://github.com/mcollina/msgpack5/releases/tag/v6.1.0 x_refsource_MISC