Symfony XXE security vulnerability

Exploitation

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

CVSS

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

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Symfony 2.0.11 carried a [similar] XXE security fix, however, on review of ZF2 I also noted a vulnerability to XML Entity Expansion (XEE) attacks whereby all extensions making use of libxml2 have no defense against XEE Quadratic Blowup Attacks. The vulnerability is a function of there being no current method of disabling custom entities in PHP (i.e. defined internal to the XML document without using external entities). In a QBA, a long entity can be defined and then referred to multiple times in document elements, creating a memory sink with which Denial Of Service attacks against a host's RAM can be mounted. The use of the LIBXMLNOENT or equivalent option in a dependent extension amplified the impact (it doesn't actually mean "No Entities"). In addition, libxml2's innate defense against the related Exponential or Billion Laugh's XEE attacks is active only so long as the LIBXMLPARSEHUGE is NOT set (it disables libxml2's hardcoded entity recursion limit). No instances of these two…

Published by the source

30 May 2024, 00:49 UTC

Last modified by the source

30 May 2024, 00:49 UTC

Source last checked

26 Oct 2026, 14:25 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-rjpm-qmq7-q85w

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# Patch Next advisory brief: GHSA-rjpm-qmq7-q85w

Advisory: Symfony XXE security vulnerability
IDs: GHSA-rjpm-qmq7-q85w
Record: https://patchnext.com/advisories/ghsa-rjpm-qmq7-q85w (revision 1, source checked 26 Oct 2026, 14:25 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: symfony/routing 2.0.17. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist symfony/routing: affected >= 2.0.0, < 2.0.17; fixed in 2.0.17

## Suggested inspection (read-only)
- Packagist symfony/routing: 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/routing.
- 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-rjpm-qmq7-q85w (GitHub-reviewed advisory GHSA-rjpm-qmq7-q85w lists affected ranges: Packagist symfony/routing >=2.0.0 <2.0.17)

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