CVE-2021-42551: Cross-site Scripting (XSS) vulnerability in the search functionality of AlCoda NetBiblio WebOPAC allows an una

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MEDIUM 6.1UPGRADE

CVE-2021-42551 is a medium-severity flaw (CVSS 6.1) affecting netbiblio. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Cross-site Scripting (XSS) vulnerability in the search functionality of AlCoda NetBiblio WebOPAC allows an unauthenticated user to craft a reflected Cross-Site Scripting attack. This issue affects: AlCoda NetBiblio WebOPAC versions prior to 4.0.0.320; versions later than 4.0.0.328. This issue does not affect: AlCoda NetBiblio WebOPAC version 4.0.0.335 and later versions.

Why this priority

Public exploit reference

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	2.7% (top 14%)
CISA exploited list	No
Weakness	CWE-79
Published	2022-01-14
Last modified	2026-06-17

Publisher (CNA): Switzerland Government Common Vulnerability Program · Vendor: alcoda

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

Am I affected?

Timeline

2022-01-14 10:15 UTCPublished CVE record published
2026-06-17 04:09 UTCUpdated Record last modified

alcoda netbiblio UPGRADE

Affected: < 4.0.0.320 · >= 4.0.0.328 and < 4.0.0.335

Fixed in: 4.0.0.320, 4.0.0.335

Safe to downgrade to: a release before 4.0.0.328

1. Check installed version

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

2. UPGRADE to 4.0.0.320 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade netbiblio

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 4.0.0.328 (Debian / Ubuntu)

apt-cache madison netbiblio sudo apt install netbiblio=<VERSION_BEFORE_4.0.0.328> sudo apt-mark hold netbiblio

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

dnf --showduplicates list netbiblio sudo dnf downgrade netbiblio-<VERSION_BEFORE_4.0.0.328> sudo dnf versionlock add netbiblio

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.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Nuclei scan template: NetBiblio WebOPAC - Cross-Site Scripting

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-2021-42551?

netbiblio: upgrade to 4.0.0.320, 4.0.0.335. Exact commands for each OS are on this page.

Is CVE-2021-42551 being exploited?

CVE-2021-42551 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-2021-42551 affect?

CVE-2021-42551 affects netbiblio. Severity is medium (CVSS 6.1). Cross-site Scripting (XSS) vulnerability in the search functionality of AlCoda NetBiblio WebOPAC allows an unauthenticated user to craft a reflected Cross-Site Scripting attack. This issue affects: AlCoda NetBiblio WebOPAC versions prior to

How urgent is CVE-2021-42551?

Priority 48/100. Public exploit reference

References

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