CVE-2026-3960: A critical remote code execution vulnerability exists in the unauthenticated REST API endpoint /99/ImportSQLTa

Q: How do I fix CVE-2026-3960?

h2o: upgrade to 3.46.0.10. Exact commands for each OS are on this page.

Q: Is CVE-2026-3960 being exploited?

CVE-2026-3960 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-3960 affect?

CVE-2026-3960 affects h2o. Severity is critical (CVSS 9.8). 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

Q: How urgent is CVE-2026-3960?

Priority 59/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

CRITICAL 9.8REMOTEUPGRADE

CVE-2026-3960 is a critical-severity flaw (CVSS 9.8) affecting h2o. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.9% (top 39%)
CISA exploited list	No
Weakness	CWE-94
Published	2026-04-23
Last modified	2026-10-26

Publisher (CNA): huntr.dev · Vendor: h2o

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-23 10:16 UTCPublished CVE record published
2026-10-26 22:10 UTCUpdated Record last modified

h2o h2o UPGRADE

Affected: < 3.46.0.10

Fixed in: 3.46.0.10

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy h2o || rpm -q h2o || h2o --version

2. UPGRADE to 3.46.0.10 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade h2o

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade h2o

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Exact fixes by distribution

Maven · ai.h2o:h2o-core · FIXED · 3.46.0.10 · vulnerable: < 3.46.0.10 · source

Set ai.h2o:h2o-core to 3.46.0.10 or later in pom.xml or build.gradle, then rebuild and redeploy.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-3960?

h2o: upgrade to 3.46.0.10. Exact commands for each OS are on this page.

Is CVE-2026-3960 being exploited?

CVE-2026-3960 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-3960 affect?

CVE-2026-3960 affects h2o. Severity is critical (CVSS 9.8). 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

How urgent is CVE-2026-3960?

Priority 59/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

MySQL vulnerabilities · PostgreSQL vulnerabilities

References

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