RCE in Symfony

Exploitation

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

CVSS

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

EPSS

• CVE-2020-15094: 3.04% estimated exploitation activity in the next 30 days; percentile 87.55 (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 ----------- The CachingHttpClient class from the HttpClient Symfony component relies on the HttpCache class to handle requests. HttpCache uses internal headers like X-Body-Eval and X-Body-File to control the restoration of cached responses. The class was initially written with surrogate caching and ESI support in mind (all HTTP calls come from a trusted backend in that scenario). But when used by CachingHttpClient and if an attacker can control the response for a request being made by the CachingHttpClient, remote code execution is possible. Resolution ---------- HTTP headers designed for internal use in HttpCache are now stripped from remote responses before being passed to HttpCache. The patch for this issue is available here for the 4.4 branch. Credits ------- I would like to thank Matthias Pigulla (webfactory GmbH) for reporting and fixing the issue.

Published by the source

2 Sep 2020, 17:29 UTC

Last modified by the source

15 Feb 2024, 05:06 UTC

Source last checked

26 Oct 2026, 14:18 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-754h-5r27-7x3r

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# Patch Next advisory brief: CVE-2020-15094

Advisory: RCE in Symfony
IDs: CVE-2020-15094, GHSA-754h-5r27-7x3r
Record: https://patchnext.com/advisories/cve-2020-15094 (revision 1, source checked 26 Oct 2026, 14:18 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: symfony/symfony 5.1.5, 4.4.13; symfony/http-kernel 5.1.5, 4.4.13. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist symfony/symfony: affected >= 5.0.0, < 5.1.5; >= 4.3.0, < 4.4.13; fixed in 5.1.5, 4.4.13
- Packagist symfony/http-kernel: affected >= 5.0.0, < 5.1.5; >= 4.3.0, < 4.4.13; fixed in 5.1.5, 4.4.13

## Suggested inspection (read-only)
- Packagist symfony/symfony: check the installed version with your package manager.
- Packagist symfony/http-kernel: 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/symfony, symfony/http-kernel.
- 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-754h-5r27-7x3r (GitHub-reviewed advisory GHSA-754h-5r27-7x3r lists affected ranges: Packagist symfony/http-kernel >=5.0.0 =4.3.0 =5.0.0 =4.3.0 <4.4.13)

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