CVE-2026-118516sensiolabs symfony interpretation conflict
CVE-2026-118516 is a interpretation conflict in sensiolabs symfony, rated medium (6.3 on CVSS 4.0).
Why this priority: Medium severity, with no exploitation signal.
Published · Updated · NVD status: Awaiting Analysis
What it is
Two components read the same input differently, and an attacker exploits the gap. A permission check exists but gets the answer wrong for some callers.
How it is reached
An attacker can exploit it over the network, without an account, and nobody has to click anything. Success also depends on conditions the attacker does not fully control.
What an attacker gains
The direct impact is limited: partial access to data or a partial outage. In practice, this kind of flaw lets an attacker smuggle requests past the proxy's checks.
Is it being exploited?
There is no public report of exploitation yet. EPSS estimates a 0.45% chance of exploitation activity in the next 30 days, higher than 39% of scored CVEs.
What to do
- No fixed version is listed yet. Find every place sensiolabs symfony runs, watch the references for a fix, and plan a replacement if it is no longer supported.
- While there is no fix, keep it off the internet or behind a VPN, allowlist or authenticating proxy.
Description from NVD
The Symfony Routing components CompiledUrlMatcher and UrlMatcher interpret the host and path information differently, allowing path-based authorization rules to be bypassed in Symfony versions prior to 5.4.56, 6.x prior to 6.4.50, 7.x prior to 7.4.23, and 8.x prior to 8.1.11.
For routes that define a host, CompiledUrlMatcher matches the string $host.'.'.$pathinfo against the host regular expression followed by the path regular expression, while UrlMatcher matches the host and the path separately. A host placeholder can therefore match /, and consume the beginning of the path, so the request is routed to a controller, while UrlMatcher would find no route. Rules that look at the path, such as access_control entries and firewall patterns, are evaluated against the actual request path, so they do not apply while the controller of the route runs, potentially allowing an unauthenticated request to reach a protected controller. For example, with the route /admin/report/{id}, the host app.{domain} and the rule access_control: [{ path: ^/admin, roles: ROLE_ADMIN }], an anonymous request for /admin/report/1 is sent to the login page. A request with the Host header app and path /x./admin/report/1 instead reaches the controller, with domain="/x". With the required domain: .+, the real hostname works: app.example.com and /x./admin/report/1 match with domain="example.com./x".
Applications are affected if they have routes with host placeholders protected by path-based rules. With the default requirement, the Host header must be the host of the route without its last labels, such as app: framework.trusted_hosts blocks that, while a web server that only serves known names may not, for instance, Nginx passing the raw Host header to FastCGI for a request line that carries an absolute URI. If the requirement accepts /, such as .+, a real hostname works, and trusted_hosts does not help.
What this means for your architecture.
A CVE names a product. Whether it matters depends on where that product sits in your systems: what reaches it, which trust boundary it guards and what it can reach once compromised. Veriom maps your components, their relationships and your trust boundaries from your code, cloud and delivery evidence, so you can see where a component like this sits. The radar itself does not look at your systems.
Components it touches
- Proxies, load balancers and the servers behind them. The flaw sits between a front-end proxy and its back end.
- Permission checks in APIs and admin surfaces. The flaw sits between one role or tenant and another.
- Multi-tenant services. The flaw sits between one role or tenant and another.
Trust boundaries in play
- Internet-facing entry points. No account is needed. Any instance reachable from outside your perimeter, through a load balancer, gateway, VPN or exposed admin port, is in scope.
- Between a front-end proxy and its back end. An attacker who crosses it can smuggle requests past the proxy's checks.
- Between one role or tenant and another. An attacker who crosses it can reach data or actions their role should not allow.
Questions to answer about your own systems
- Where does sensiolabs symfony run in your systems, and at which version?
- Which of those instances can be reached from the internet or partner networks?
- What can it reach once compromised: which data stores, secrets and services?
Read more
Sources
- CVE records and CVSS scores from the NVD CVE API. This product uses the NVD API but is not endorsed or certified by the NVD.
- Exploitation status from CISA’s Known Exploited Vulnerabilities catalog.
- Exploit likelihood from FIRST’s Exploit Prediction Scoring System (EPSS), refreshed daily.
- Explanations are written by Veriom from fixed templates over each record’s data, not by a person reviewing each CVE. Descriptions are quoted from the records as published.