CVE-2021-42943: Stored cross-site scripting (XSS) in admin/usermanager.php over IPPlan v4.92b allows remote attackers to injec

Routine

MEDIUM 5.4DOWNGRADE

CVE-2021-42943 is a medium-severity flaw (CVSS 5.4) affecting ipplan. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Stored cross-site scripting (XSS) in admin/usermanager.php over IPPlan v4.92b allows remote attackers to inject arbitrary web script or HTML via the userid parameter.

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.7% (top 45%)
CISA exploited list	No
Weakness	CWE-79
Published	2022-05-17
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: ipplan project

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

Am I affected?

Timeline

2022-05-17 11:15 UTCPublished CVE record published
2026-06-17 04:10 UTCUpdated Record last modified

ipplan project ipplan DOWNGRADE

Affected: 4.92b

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.92b

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 4.92b (Debian / Ubuntu)

apt-cache madison ipplan sudo apt install ipplan=<VERSION_BEFORE_4.92b> sudo apt-mark hold ipplan

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list ipplan sudo dnf downgrade ipplan-<VERSION_BEFORE_4.92b> sudo dnf versionlock add ipplan

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-2021-42943?

ipplan: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-42943 being exploited?

CVE-2021-42943 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-2021-42943 affect?

CVE-2021-42943 affects ipplan. Severity is medium (CVSS 5.4). Stored cross-site scripting (XSS) in admin/usermanager.php over IPPlan v4.92b allows remote attackers to inject arbitrary web script or HTML via the userid parameter.

How urgent is CVE-2021-42943?

Priority 38/100. Public exploit reference

Software pages

PHP vulnerabilities

References

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