CVE-2025-6544 | Deserialization Vulnerability in h2oai/h2o-3

Exp

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.

Published: 2025-09-21 Last update: 2025-10-08 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2025-6544 is rated High Exploit Risk (78.4/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 0.57%). Core evidence: 1 public exploit reference(s) are indexed (Exploit-DB). Mandatory action: Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2025-6544

EDB-ID Source Kind Published Link
nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2025-6544

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-27 0.47% 0.57% +0.10%
2 2026-04-17 0.42% 0.47% +0.05%
3 2026-03-01 0.42%

Full EPSS history (8 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-6544

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.0 CRITICAL
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
3.9 5.9 [email protected]

Weakness enumeration for CVE-2025-6544

GitHub Security Advisory for CVE-2025-6544

GHSA-5w3j-gwgh-4rfv · Severity: critical · Ecosystem: maven — H2O affected by a deserialization vulnerability

Affected software / configurations for CVE-2025-6544

Vendor Product Version Raw CPE
h2o h2o >= 3.0.0.2, <= 3.46.0.8 cpe:2.3:a:h2o:h2o:*:*:*:*:*:*:*:*

References for CVE-2025-6544

cvelogic Threat Intelligence