CVE-2026-90473: msgpack-java through 0.9.12 Integer Overflow via MAP32

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-12 · updated 2026-09-23
Weakness: CWE-190

Description

msgpack-java through 0.9.12 contains an integer overflow vulnerability in MessageUnpacker.skipValue() when processing MAP32 containers with large element counts. Attackers can supply a MAP32 element count at or above 0x40000000 that wraps when doubled, causing the parser cursor to desynchronize and attacker-controlled data to be returned in place of later fields.

Affected products

msgpack-java: through 0.9.12

References

https://github.com/msgpack/msgpack-java
https://github.com/msgpack/msgpack-java/blob/v0.9.12/msgpack-core/src/main/java/org/msgpack/core/MessageUnpacker.java#L573-L581
https://github.com/msgpack/msgpack-java/issues/1014
https://www.vulncheck.com/advisories/msgpack-java-through-0.9.12-integer-overflow-via-map32

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