CVE-2025-3902: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Drupal B

Routine

MEDIUM 6.1UPGRADE

CVE-2025-3902 is a medium-severity flaw (CVSS 6.1) affecting block class. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Drupal Block Class allows Cross-Site Scripting (XSS).This issue affects Block Class: from 4.0.0 before 4.0.1.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.2% (top 84%)
CISA exploited list	No
Weakness	CWE-79
Published	2025-04-23
Last modified	2026-06-17

Publisher (CNA): Drupal.org · Vendor: four kitchens

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-04-23 17:16 UTCPublished CVE record published
2026-06-17 09:20 UTCUpdated Record last modified

four kitchens block class UPGRADE

Affected: >= 4.0.0 and < 4.0.1

Fixed in: 4.0.1

Safe to downgrade to: a release before 4.0.0

1. Check installed version

apt-cache policy block-class || rpm -q block-class || block-class --version

2. UPGRADE to 4.0.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade block-class

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade block-class

Note

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

3. If no update is available yet, DOWNGRADE to a release before 4.0.0 (Debian / Ubuntu)

apt-cache madison block-class sudo apt install block-class=<VERSION_BEFORE_4.0.0> sudo apt-mark hold block-class

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list block-class sudo dnf downgrade block-class-<VERSION_BEFORE_4.0.0> sudo dnf versionlock add block-class

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2025-3902?

block class: upgrade to 4.0.1. Exact commands for each OS are on this page.

Is CVE-2025-3902 being exploited?

CVE-2025-3902 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-2025-3902 affect?

CVE-2025-3902 affects block class. Severity is medium (CVSS 6.1). Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Drupal Block Class allows Cross-Site Scripting (XSS).This issue affects Block Class: from 4.0.0 before 4.0.1.

How urgent is CVE-2025-3902?

Priority 25/100. No elevated risk signals yet.

Software pages

Drupal vulnerabilities

References

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