What’s Vulnerable › Vulnerabilities

CVE-2026-107302: msgpack5: Truncated map32 headers throw an unexpected error

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-08 · updated 2026-10-19
• Weakness: CWE-125

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 products

• mcollina msgpack5: from 4.1.0. < 6.1.0

References

• https://github.com/mcollina/msgpack5/commit/15443a1f2aa682a6aa37f1705ac628de5b866ad1
• https://github.com/mcollina/msgpack5/releases/tag/v6.1.0
• https://github.com/mcollina/msgpack5/security/advisories/GHSA-8f34-f56x-9xph

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