Deserialization Vulnerability in H2O.ai H2O-3 Affects Multiple Versions
CVE-2025-6544

9.8CRITICAL

Key Information:

Vendor

H2oai

Status
H2oai/h2o-3
Vendor
CVE Published:
21 September 2025

What is CVE-2025-6544?

A deserialization vulnerability in H2O.ai's H2O-3 versions up to 3.46.0.8 allows attackers to exploit JDBC connection parameters. This weakness enables unauthorized access to arbitrary system files and the potential execution of malicious code. Attackers can bypass traditional regular expression filtering through double URL encoding, impacting all users on the affected versions. Prompt updating is recommended to mitigate risks associated with this vulnerability.

Affected Version(s)

h2oai/h2o-3 < 3.46.8

References

https://huntr.com/bounties/53f35a0f-d644-4f82-93aa-89fe7e...
https://github.com/h2oai/h2o-3/commit/0298ee348f5c73673b7...

CVSS V3.0

Score:
9.8
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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CVE-2025-6544 : Deserialization Vulnerability in H2O.ai H2O-3 Affects Multiple Versions