CVE-2020-28246: A Server-Side Template Injection (SSTI) was discovered in Form.io 2.0.0

This week

CRITICAL 9.8REMOTEDOWNGRADE

CVE-2020-28246 is a critical-severity flaw (CVSS 9.8) affecting form.io. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A Server-Side Template Injection (SSTI) was discovered in Form.io 2.0.0. This leads to Remote Code Execution during deletion of the default Email template URL. NOTE: the email templating service was removed after 2020. Additionally, the vendor disputes this issue indicating this is sandboxed and only executable by admins.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.4% (top 16%)
CISA exploited list	No
Weakness	CWE-74
Published	2022-06-02
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: form

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

Am I affected?

Timeline

2022-06-02 14:15 UTCPublished CVE record published
2026-06-17 03:10 UTCUpdated Record last modified

form form.io DOWNGRADE

Affected: 2.0.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.0.0

1. Check installed version

apt-cache policy form.io || rpm -q form.io || form.io --version

2. No fixed release: DOWNGRADE to a release before 2.0.0 (Debian / Ubuntu)

apt-cache madison form.io sudo apt install form.io=<VERSION_BEFORE_2.0.0> sudo apt-mark hold form.io

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

dnf --showduplicates list form.io sudo dnf downgrade form.io-<VERSION_BEFORE_2.0.0> sudo dnf versionlock add form.io

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-2020-28246?

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

Is CVE-2020-28246 being exploited?

CVE-2020-28246 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-2020-28246 affect?

CVE-2020-28246 affects form.io. Severity is critical (CVSS 9.8). A Server-Side Template Injection (SSTI) was discovered in Form.io 2.0.0. This leads to Remote Code Execution during deletion of the default Email template URL. NOTE: the email templating service was removed after 2020. Additionally, the ven

How urgent is CVE-2020-28246?

Priority 60/100. Critical severity; Remotely exploitable, no login, no user action

References

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