CVE•Published 2025-09-21•Modified 2026-10-05•1 article on news•7 live references•NVD data

CVE-2025-6544H2o · H2o

Vulnerability data via NVD (ingested)

CVSS v3.1

9.8

CRITICAL

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS percentile

Exploit Prediction Scoring System · top 41% of all CVEs

Weaknesses (CWE)

CWE-502Deserialization of Untrusted Data

Description

A deserialization vulnerability exists in h2oai/h2o-3 versions <= 3.46.0.8, allowing attackers to read arbitrary system files and execute arbitrary code. The vulnerability arises from improper handling of JDBC connection parameters, which can be exploited by bypassing regular expression checks and using double URL encoding. This issue impacts all users of the affected versions.

Timeline

Published 2025-09-21

Modified 2026-10-05

External references

NVD MITRE Exploit-DB GitHub PoC Sploitus trickest/cve VulnCheck

Search for exposed instances

Shodan + Censys queries derived from NVD's CPE data. The vuln tag catches assets Shodan has explicitly linked to this CVE; the product / banner fingerprints find exposed instances even when the vuln tag was never applied (which is common).

Shodan · vuln tag0 hosts

vuln:CVE-2025-6544

Hosts Shodan has explicitly fingerprinted as vulnerable.

Shodan · product

product:"H2o H2o"

All exposed H2o H2o instances — cross-reference with the CVE's affected-version range.

Shodan · banner/body mention

http.html:"H2o"

HTTP body or banner mentions "H2o" — catches deploys Shodan didn't identify as a product.

More intel sources (5)

Shodan report

vuln:CVE-2025-6544