Skip to main content

Boteraser | Website and Server Security Solutions

🛡️ CVE-2026-3960 — h2o

🔴 CVSS 9.8 — Critical ✅ No Known Exploit CWE-94 OSV
9.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

H2O-3 is Vulnerable to Code Injection

A critical remote code execution vulnerability exists in the unauthenticated REST API endpoint /99/ImportSQLTable in H2O-3 version 3.46.0.9 and prior. The vulnerability arises due to insufficient security controls in the parameter blacklist mechanism, which only targets MySQL JDBC driver-specific dangerous parameters. An attacker can bypass these controls by switching the JDBC URL protocol to jdbc:postgresql: and exploiting PostgreSQL JDBC driver-specific parameters such as socketFactory and socketFactoryArg. This allows unauthenticated attackers to execute arbitrary code on the H2O-3 server with the privileges of the H2O-3 process. The issue is resolved in version 3.46.0.10.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: High — the attacker first has to win a race, learn a secret or otherwise prepare the target.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: None.
  • Integrity impact: None.
  • Availability impact: High — total loss, or loss the attacker controls.

Weakness class

CVE-2026-3960 is classified as CWE-94: Code Injection. Input is incorporated into code that the runtime evaluates, so an attacker can have their own code executed.

Affected software

CVE-2026-3960 is recorded against 2 packages.

  • ai.h2o:h2o-core (fixed in 3.46.0.10)
  • h2o (fixed in 3.46.0.10)

Timeline and source

Published on 23 April 2026 and last revised on 13 July 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

nvd.nist.gov (Advisory)
github.com (Web)
github.com (Package)
huntr.com (Web)

Other advisories for this package

ai.h2o:h2o-core has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-94: Code Injection) in other software:

Details

Severity Critical
CVSS Score 9.8
CVSS Vector CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE CWE-94
Public Exploit ✅ No
Source OSV
Published 2026-04-23
Updated 2026-08-20
Modified 2026-07-13
Fix URL N/A

Affected Packages

Software From version Fixed in
ai.h2o:h2o-core — 3.46.0.10
h2o — 3.46.0.10

Similar Threats

Exploit Protection

Are you running h2o?

CVE-2026-3960 carries CVSS 9.8 Critical rating. BotEraser checks your installation against this and other known CVE records, and blocks IPs associated with exploit activity.

Check My Site For CVE-2026-3960 →

No credit card required  ·  Results in minutes

ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

Browse related advisories

All advisoriesCVECVE 2026
✓