high CVSS 7.5 EPSS 0.60%

CVE-2026-48489·PHP vulnerability

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to 5.4.53, 6.4.41, 7.4.13, and 8.0.13, DefaultAuthenticationFailureHandler honored the request-supplied _failure_path parameter when failure_forward: true was enabled, allowing an unauthenticated failing login request to dispatch a subrequest to access_control-protected GET routes that skipped firewall listeners. This issue is fixed in versions 5.4.53, 6.4.41, 7.4.13, and 8.0.13.

Severity
high
Software
PHP
Fixed in
8.0.13
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at 0.60% — higher than 46% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Read the two together. CVE-2026-48489 scores 7.5 on CVSS, so a successful attack would be serious — but at 0.60%, almost nobody is currently attempting it. That is a different situation from a flaw under mass exploitation, and it is usually the difference between patching on your next maintenance window and patching tonight.

Affected versions

From: 8.0.0

Until: 8.0.13

Fixed in: 8.0.13

How to fix this CVE

Update PHP and Symfony to versions 8.0.13 or later to patch a critical authentication bypass in the DefaultAuthenticationFailureHandler. This vulnerability allows attackers to bypass firewall protection by manipulating the failure redirect path during failed login attempts. Immediately apply the security patch to prevent unauthorized access to protected routes.

sudo dnf update php

Defensia detects this vulnerability

What an exploitation attempt looks like

Sample log line indicative of exploitation attempts:

POST /login_check followed by GET requests to /admin/* or other access-controlled routes with _failure_path parameter in the request URL, originating from sessions without prior successful authentication tokens

WAF mitigation (if patching is not yet possible)

Add this rule to your WAF to block exploitation attempts while you schedule the patch. 

Implement WAF rules to block GET requests containing the _failure_path parameter to access-controlled routes, or restrict the _failure_path parameter value to whitelisted internal URLs only

How to check if you are affected

  1. Step 1: Check your PHP version with `php -v` and verify Symfony version in composer.lock or via `composer show symfony/symfony`
  2. Step 2: Search your application codebase for DefaultAuthenticationFailureHandler configuration and verify if `failure_forward: true` is enabled in security.yaml
  3. Step 3: Review web server access logs for GET requests to access-controlled routes originating from unauthenticated sessions, particularly those with _failure_path parameters
  4. Step 4: After patching, confirm the update with `php -v` and `composer show symfony/symfony` to ensure version 8.0.13 or higher is installed

FAQ

What is CVE-2026-48489?

CVE-2026-48489 is an authentication bypass vulnerability in Symfony's DefaultAuthenticationFailureHandler that allows unauthenticated users to access firewall-protected routes by manipulating the failure redirect parameter when the failure_forward option is enabled.

Is CVE-2026-48489 being actively exploited?

No, CVE-2026-48489 is not currently listed in CISA's Known Exploited Vulnerabilities (KEV) catalog and no public exploits are available, though the vulnerability is straightforward to exploit once discovered.

What versions of PHP/Symfony are affected by CVE-2026-48489?

Symfony versions 8.0.0 through 8.0.12 are affected. Earlier branches (5.x, 6.x, 7.x) require patching to versions 5.4.53, 6.4.41, and 7.4.13 respectively.

How do I check if my server is vulnerable to CVE-2026-48489?

Run `composer show symfony/symfony` and check if the version is below 8.0.13; if so, verify that `failure_forward: true` is configured in your security settings. Both conditions must be present for the vulnerability to be exploitable.

Does Defensia detect CVE-2026-48489?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If PHP and Symfony are installed on a monitored server, CVE-2026-48489 will appear in your dashboard with remediation steps.

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References

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