{"id":"CVE-2025-6544","title":"A deserialization vulnerability exists in h2oai/h2o-3 versions <= 3.46.0.8, allowing attackers to read arbitrary system files and execute arbitrary code","summary":"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, whic…","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-502"],"vendor":"h2o","product":"h2o","affected":["h2o >= 3.0.0.2, <= 3.46.0.8"],"published":"2025-09-21","updated":"2026-10-01","sourceUpdated":"2026-10-01T16:10:00.257","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2025-6544","references":[{"url":"https://github.com/h2oai/h2o-3/commit/0298ee348f5c73673b7b542158081e79605f5f25","label":"security@huntr.dev"},{"url":"https://huntr.com/bounties/53f35a0f-d644-4f82-93aa-89fe7e0aed40","label":"security@huntr.dev"},{"url":"https://huntr.com/bounties/53f35a0f-d644-4f82-93aa-89fe7e0aed40","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"tags":["nvd"],"epss":0.00919,"epssPercentile":0.58808,"ingestedAt":"2026-10-01T18:55:42.287Z","slug":"CVE-2025-6544","body":"## Overview\n\nA 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.\n\n## Affected\n\n- `h2o >= 3.0.0.2, <= 3.46.0.8`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.2,"exploitation":0,"ransomware":0},"changes":[]}