Integer overflow in Msgpack Msgpack-Java
CVE-2026-90473
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.
Vulnerability class: Integer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.004 (35.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 35th percentile — 35.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
Weakness classification (CWE)
References
- github.com/msgpack/msgpack-java (product)
- github.com/msgpack/msgpack-java/blob/v0.9.12/msgpack-core/src/main/java/org/msg… (technical-description)
- github.com/msgpack/msgpack-java/issues/1014 (issue-tracking)
- www.vulncheck.com/advisories/msgpack-java-through-0.9.12-integer-overflow-via-m… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-90473?
- CVE-2026-90473 is a medium-severity vulnerability in Msgpack Msgpack-Java, classified under Integer Overflow or Wraparound. CVSS score: 5.3/10. Published 2026-09-12.
- How severe is CVE-2026-90473?
- Medium severity. CVSS v3 base score is 5.3 out of 10.