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Critical, CVSS 9.8amended

Server-Side Template Injection in formio

CVE-2020-28246GHSA-52vj-mr2j-f8jh

What to do

Vendor response not established. Follow the primary source's mitigation guidance and check back for a fix.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • npm formio

    Affected
    <= 2.0.0
    Fixed in
    no fixed version recorded

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
9.8 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
  • CVE-2020-28246: 2.44% estimated exploitation activity in the next 30 days; percentile 84.30 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

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.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-52vj-mr2j-f8jh

  2. Revision 1 · created ·

    Published from osv record GHSA-52vj-mr2j-f8jh

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2020-28246

Advisory: Server-Side Template Injection in formio
IDs: CVE-2020-28246, GHSA-52vj-mr2j-f8jh
Record: https://patchnext.com/advisories/cve-2020-28246 (revision 2, source checked 26 Oct 2026, 12:30 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm formio: affected <= 2.0.0

## Suggested inspection (read-only)
- `npm ls formio --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on formio.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-52vj-mr2j-f8jh (OSV record GHSA-52vj-mr2j-f8jh lists affected ranges: npm formio >=0 <=2.0.0)
- Verified: https://github.com/advisories/GHSA-52vj-mr2j-f8jh (GitHub-reviewed advisory GHSA-52vj-mr2j-f8jh lists affected ranges: npm formio >=0 <=2.0.0)

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