Exceptions displayed in non-debug configurations in Symfony

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

4.6 · CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

EPSS

• CVE-2020-5274: 1.20% estimated exploitation activity in the next 30 days; percentile 68.14 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Description ----------- When ErrorHandler renders an exception HTML page, it uses un-escaped properties from the related Exception class to render the stacktrace. The security issue comes from the fact that the stacktraces were also displayed in non-debug environments. Resolution ---------- The ErrorHandler class now escapes all properties coming from the related Exception, and the stacktrace is not displayed anymore in non-debug environments. The patches for this issue are available here and here for branch 4.4. Credits ------- I would like to thank Luka Sikic for reporting & Yonel Ceruto and Jérémy Derussé for fixing the issue.

Published by the source

30 Mar 2020, 20:09 UTC

Last modified by the source

6 Feb 2024, 13:30 UTC

Source last checked

26 Oct 2026, 14:15 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-m884-279h-32v2

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# Patch Next advisory brief: CVE-2020-5274

Advisory: Exceptions displayed in non-debug configurations in Symfony
IDs: CVE-2020-5274, GHSA-m884-279h-32v2
Record: https://patchnext.com/advisories/cve-2020-5274 (revision 1, source checked 26 Oct 2026, 14:15 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: symfony/error-handler 5.0.4, 4.4.4; symfony/symfony 5.0.4, 4.4.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist symfony/error-handler: affected >= 4.4.0, < 4.4.4; >= 5.0.0, < 5.0.4; fixed in 4.4.4, 5.0.4
- Packagist symfony/symfony: affected >= 4.4.0, < 4.4.4; >= 5.0.0, < 5.0.4; fixed in 4.4.4, 5.0.4

## Suggested inspection (read-only)
- Packagist symfony/error-handler: check the installed version with your package manager.
- Packagist symfony/symfony: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on symfony/error-handler, symfony/symfony.
- 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://github.com/advisories/GHSA-m884-279h-32v2 (GitHub-reviewed advisory GHSA-m884-279h-32v2 lists affected ranges: Packagist symfony/error-handler >=4.4.0 =5.0.0 =4.4.0 =5.0.0 <5.0.4)

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