CVE-2025-6544

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.

CVSS v3.1 Score

9.8

CRITICAL

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

Weakness Type (CWE)

CWE-502 Deserialization of Untrusted Data

Affected Products

Vendor	Product	Versions
h2o	h2o	3.0.0.2 — 3.46.0.8

References

Advisories & Patches

https://github.com/h2oai/h2o-3/commit/0298ee348f5c73673b7b542158081e79605f5f25

Exploits

https://huntr.com/bounties/53f35a0f-d644-4f82-93aa-89fe7e0aed40 https://huntr.com/bounties/53f35a0f-d644-4f82-93aa-89fe7e0aed40

Frequently Asked Questions

What is CVE-2025-6544? +

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. It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2025-6544? +

CVE-2025-6544 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately.

What products are affected by CVE-2025-6544? +

CVE-2025-6544 affects products from h2o, specifically: h2o. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-6544? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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