CVE-2026-48489High▾ TwilightSymfony: Security Firewall Bypass via failure_forward Subrequest: Unauthenticated Access to access_control-Protected GET Routes
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 41.3 · likelihood 0.1 · exploitation 0
Need a working PoC? Pro members can cast a request and our team develops one — it lands right here.
Exploit-prediction probability, daily snapshots since Jul 15.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via GHSA
0.5%
0.5% → 0.6%
When a firewall is configured with form-login (or any authenticator using DefaultAuthenticationFailureHandler) and the failure_forward: true option, the handler reads the _failure_path parameter from the failing login request and uses it as the path of an internal subrequest dispatched through HttpKernelInterface::SUB_REQUEST.
Symfony's Firewall::onKernelRequest listener intentionally skips subrequests under the assumption they are internally generated and trusted, which also means AccessListener (the listener that evaluates access_control) does not run. Because the attacker controls the target of the subrequest, an unauthenticated POST to the check path with _failure_path=/admin/whatever performs a local request forgery that executes the target controller outside the firewall perimeter and returns its response to the caller.
Applications that follow Symfony's recommended best practice of protecting administrative areas with broad access_control rules (e.g. ^/admin requires ROLE_ADMIN) and expose read-only GET endpoints under that area (data exports, internal APIs, account views) are fully exposed: any such GET route can be read by an unauthenticated attacker without any developer misconfiguration, debug mode, or state-changing GET handler being required.
DefaultAuthenticationFailureHandler no longer honors the request-supplied _failure_path parameter when failure_forward is enabled. The subrequest is always dispatched to the configured failure_path option (defaulting to login_path), which is set by the application owner and not by the request. The redirect branch (failure_forward: false) is unchanged because redirects re-enter the firewall on the next request and are not subject to this bypass.
The patch for this issue is available here for branch 5.4.
Symfony would like to thank Nguyen Ngoc Toan Thang (@a-tt-om) and Tran Quoc Tri Trung (@teebow1e) for reporting the issue, and Nicolas Grekas for providing the fix.
symfony/security-http < 5.4.53symfony/symfony < 5.4.53symfony/security-http >= 6.0.0, < 6.4.41symfony/security-http >= 7.0.0, < 7.4.13symfony/security-http >= 8.0.0, < 8.0.13symfony/symfony >= 6.0.0, < 6.4.41symfony/symfony >= 7.0.0, < 7.4.13symfony/symfony >= 8.0.0, < 8.0.13Upgrade to a patched release:
symfony/security-http 5.4.53symfony/symfony 5.4.53symfony/security-http 6.4.41symfony/security-http 7.4.13symfony/security-http 8.0.13symfony/symfony 6.4.41symfony/symfony 7.4.13symfony/symfony 8.0.13Connected by shared product, vendor, weakness, or advisory.
CVE-2020-3578Medium· 5.3A vulnerability in the web services interface of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass a configured access rule and ac…
CVE-2024-6593Critical· 9.1Incorrect Authorization vulnerability in WatchGuard Authentication Gateway (aka Single Sign-On Agent) on Windows allows an attacker with network access to execute restricted management commands. An attacker that has already gained netwo…
CVE-2026-47767MediumSymfonyRuntime CVE-2024-50340 Patch Bypass: Web Requests Can Still Set APP_ENV/APP_DEBUG via parse_str/SAPI Argv Mismatch
CVE-2026-48761MediumSymfony: HtmlSanitizer UrlAttributeSanitizer Misses URL Attributes
CVE-2026-48736MediumSymfony: IpUtils::PRIVATE_SUBNETS Omits IPv6 Transition Forms (6to4, NAT64, Teredo, IPv4-compatible): SSRF Bypass in NoPrivateNetworkHttpClient
CVE-2026-48747MediumSymfony: Mailomat Mailer Webhook Parser Reads the HMAC Algorithm from the Request: Signature Algorithm Downgrade