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CVE-2026-21452

MessagePack for Java is a serializer implementation for Java. A denial-of-service vulnerability exists in versions prior to 0.9.11 when deserializing .msgpack files containing EXT32 objects with attacker-controlled payload lengths. While MessagePack-Java parses extension headers lazily, it later trusts the declared EXT payload length when materializing the extension data. When ExtensionValue.getData() is invoked, the library attempts to allocate a byte array of the declared length without enforc
Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:25de30a7d42a12be202a5a4b80288c752a8f60d7ce386a4836902a79bb657784
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
1

Preserved source conflicts

No provider value was silently selected as the winner.

cwe · 2 assertions

{"cweId":"CWE-400","description":"CWE-400: Uncontrolled Resource Consumption","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:830527007177bc169c8e9eb38c97499861fabffb89513d6f8ef570f39d83abb1 · sha256:9449c00675560081… · /containers/cna/problemTypes/0/descriptions/0

{"cweId":"CWE-789","description":"CWE-789: Memory Allocation with Excessive Size Value","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:830527007177bc169c8e9eb38c97499861fabffb89513d6f8ef570f39d83abb1 · sha256:9449c00675560081… · /containers/cna/problemTypes/1/descriptions/0

Affected products and versions

1 source assertion
{"product":"msgpack-java","vendor":"msgpack","versions":[{"status":"affected","version":"< 0.9.11"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:830527007177bc169c8e9eb38c97499861fabffb89513d6f8ef570f39d83abb1 · sha256:9449c00675560081… · /containers/cna/affected/0

Provider-owned CVSS observations

1 source assertion
{"metric":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"metric_type":"cvssV3_1"}
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:830527007177bc169c8e9eb38c97499861fabffb89513d6f8ef570f39d83abb1 · sha256:9449c00675560081… · /containers/cna/metrics/0/cvssV3_1

CWE assertions

2 source assertions
{"cweId":"CWE-400","description":"CWE-400: Uncontrolled Resource Consumption","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:830527007177bc169c8e9eb38c97499861fabffb89513d6f8ef570f39d83abb1 · sha256:9449c00675560081… · /containers/cna/problemTypes/0/descriptions/0
{"cweId":"CWE-789","description":"CWE-789: Memory Allocation with Excessive Size Value","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:830527007177bc169c8e9eb38c97499861fabffb89513d6f8ef570f39d83abb1 · sha256:9449c00675560081… · /containers/cna/problemTypes/1/descriptions/0

Source references

3 source assertions
{"name":"https://github.com/msgpack/msgpack-java/commit/daa2ea6b2f11f500e22c70a22f689f7a9debdeae","tags":["x_refsource_MISC"],"url":"https://github.com/msgpack/msgpack-java/commit/daa2ea6b2f11f500e22c70a22f689f7a9debdeae"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:830527007177bc169c8e9eb38c97499861fabffb89513d6f8ef570f39d83abb1 · sha256:9449c00675560081… · /containers/cna/references/1
{"name":"https://github.com/msgpack/msgpack-java/releases/tag/v0.9.11","tags":["x_refsource_MISC"],"url":"https://github.com/msgpack/msgpack-java/releases/tag/v0.9.11"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:830527007177bc169c8e9eb38c97499861fabffb89513d6f8ef570f39d83abb1 · sha256:9449c00675560081… · /containers/cna/references/2
{"name":"https://github.com/msgpack/msgpack-java/security/advisories/GHSA-cw39-r4h6-8j3x","tags":["x_refsource_CONFIRM"],"url":"https://github.com/msgpack/msgpack-java/security/advisories/GHSA-cw39-r4h6-8j3x"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:830527007177bc169c8e9eb38c97499861fabffb89513d6f8ef570f39d83abb1 · sha256:9449c00675560081… · /containers/cna/references/0

Attribution and limitations

  • CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →

Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.

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