fixnx
mediumCVE-2026-48736

CVE-2026-48736 in Symfony HttpClient

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. From 5.4.0 to 5.4.53, 6.4.41, 7.4.13, and 8.0.13, NoPrivateNetworkHttpClient and IpUtils::PRIVATE_SUBNETS omitted IPv6 transition prefixes such as 6to4, NAT64, Teredo, and IPv4-compatible IPv6, allowing attacker-supplied URLs to represent private IPv4 targets in forms that IpUtils::isPrivateIp() did not block. This issue is fixed in versions 5.4.53, 6.4.41, 7.4.13, and 8.0.13.

ProductSymfony
CVSS6.9
EPSS0.00457
UpdatedJuly 16, 2026

Quick answer

Symfony should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.

Who is affected

Affected versions

  • Symfony 5.4 before 5.4.53
  • Symfony 6.4 before 6.4.41
  • Symfony 7.4 before 7.4.13
  • Symfony 8.0 before 8.0.13

Fixed versions

  • 5.4.53
  • 6.4.41
  • 7.4.13
  • 8.0.13

How to fix it

CVE-2026-48736 is a SSRF issue in Symfony. Update from Symfony 5.4 before 5.4.53 to 5.4.53 or newer. Keep it simple: upgrade first, then test the normal user flow.

  1. Find every place where Symfony is installed or used.
  2. Upgrade Symfony to 5.4.53 or a newer fixed release from the vendor.
  3. If you cannot upgrade right away, limit access to the affected feature until the update is done.
  4. Restart or redeploy the service if the product needs it after the update.

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Verify the fix

  • Confirm the installed version is 5.4.53 or newer.
  • Run a normal login, admin, and user flow to make sure the site still works.
  • Check logs for new errors after the update.

Related categories

PHPInput ValidationSSRF

Trusted references

Source advisoryNVDSource advisoryNVDSource advisoryNVDSource advisoryNVDSource advisoryNVDSource advisoryNVDSource advisoryNVD

FAQ

What is affected by CVE-2026-48736?

Symfony versions listed as affected should be reviewed: Symfony 5.4 before 5.4.53, Symfony 6.4 before 6.4.41, Symfony 7.4 before 7.4.13, Symfony 8.0 before 8.0.13.

What should I fix first?

Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.

How do I confirm the fix worked?

Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.

How are Fixnx security risk categories chosen?

Fixnx keeps one canonical risk page and assigns only broad, relevant categories such as ecosystem, technology area, or vulnerability class.