CVE-2021-39420: Multiple Cross Site Scripting (XSS) vulnerabilities exist in VFront 0.99.5 via the (1) s parameter in search_a

Routine

MEDIUM 6.1DOWNGRADE

CVE-2021-39420 is a medium-severity flaw (CVSS 6.1) affecting vfront. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Multiple Cross Site Scripting (XSS) vulnerabilities exist in VFront 0.99.5 via the (1) s parameter in search_all.php and the (2) msg parameter in add.attach.php.

Why this priority

Public exploit reference

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

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.7% (top 48%)
CISA exploited list	No
Weakness	CWE-79
Published	2021-11-08
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: vfront

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

Am I affected?

Timeline

2021-11-08 19:15 UTCPublished CVE record published
2026-06-17 04:03 UTCUpdated Record last modified

vfront vfront DOWNGRADE

Affected: 0.99.5

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.99.5

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.99.5 (Debian / Ubuntu)

apt-cache madison vfront sudo apt install vfront=<VERSION_BEFORE_0.99.5> sudo apt-mark hold vfront

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

dnf --showduplicates list vfront sudo dnf downgrade vfront-<VERSION_BEFORE_0.99.5> sudo dnf versionlock add vfront

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-2021-39420?

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

Is CVE-2021-39420 being exploited?

CVE-2021-39420 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-2021-39420 affect?

CVE-2021-39420 affects vfront. Severity is medium (CVSS 6.1). Multiple Cross Site Scripting (XSS) vulnerabilities exist in VFront 0.99.5 via the (1) s parameter in search_all.php and the (2) msg parameter in add.attach.php.

How urgent is CVE-2021-39420?

Priority 39/100. Public exploit reference

Software pages

PHP vulnerabilities

References

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