Medium severity · published Sep 12, 2026
CVE-2026-90473
msgpack-java through 0.9.12 Integer Overflow via MAP32
5.3
CVSS
0.4%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 35% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MS
msgpack-java · msgpack
through 0.9.12 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-90473
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-90473
github.com
https://github.com/msgpack/msgpack-java
github.com
https://github.com/msgpack/msgpack-java/blob/v0.9.12/msgpack-core/src/main/java/org/msgpack/core/MessageUnpacker.java#L573-L581
github.com
https://github.com/msgpack/msgpack-java/issues/1014
www.vulncheck.com
https://www.vulncheck.com/advisories/msgpack-java-through-0.9.12-integer-overflow-via-map32
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