CVE-2026-27739 is a low severity vulnerability with a CVSS score of 0.0. No known exploits currently, and patches are available.
Very low probability of exploitation
EPSS predicts the probability of exploitation in the next 30 days based on real-world threat data, complementing CVSS severity scores with actual risk assessment.
A Server-Side Request Forgery (SSRF) vulnerability has been identified in the Angular SSR request handling pipeline. The vulnerability exists because Angular’s internal URL reconstruction logic directly trusts and consumes user-controlled HTTP headers specifically the Host and X-Forwarded-* family to determine the application's base origin without any validation of the destination domain.
Specifically, the framework didn't have checks for the following:
Host and X-Forwarded-Host headers were not checked to belong to a trusted origin. This allows an attacker to redefine the "base" of the application to an arbitrary external domain.X-Forwarded-Host header was not checked for path segments or special characters, allowing manipulation of the base path for all resolved relative URLs.X-Forwarded-Port header was not verified as numeric, leading to malformed URI construction or injection attacks.This vulnerability manifests in two primary ways:
HttpClient resolves relative URLs against this unvalidated and potentially malformed base origin. An attacker can "steer" these requests to an external server or internal service.REQUEST object to manually construct URLs (for fetch or third-party SDKs) directly inherit these unsanitized values. By accessing the Host / X-Forwarded-* headers, the application logic may perform requests to attacker-controlled destinations or malformed endpoints.When successfully exploited, this vulnerability allows for arbitrary internal request steering. This can lead to:
Authorization headers or session cookies by redirecting them to an attacker's server.Please cite this page when referencing data from Strobes VI. Proper attribution helps support our vulnerability intelligence research.
169.254.169.254) not exposed to the public internet.HttpClient requests using relative URLs OR manually construct URLs using the unvalidated Host / X-Forwarded-* headers using the REQUEST object.req.headers for URL construction. Instead, use trusted variables for your base API paths.server.ts to enforce numeric ports and validated hostnames.const ALLOWED_HOSTS = new Set(['your-domain.com']);
app.use((req, res, next) => {
const hostHeader = (req.headers['x-forwarded-host'] ?? req.headers['host'])?.toString();
const portHeader = req.headers['x-forwarded-port']?.toString();
if (hostHeader) {
const hostname = hostHeader.split(':')[0];
// Reject if hostname contains path separators or is not in allowlist
if (/^[a-z0-9.:-]+$/i.test(hostname) ||
(!ALLOWED_HOSTS.has(hostname) && hostname !== 'localhost')) {
return res.status(400).send('Invalid Hostname');
}
}
// Ensure port is strictly numeric if provided
if (portHeader && !/^\d+$/.test(portHeader)) {
return res.status(400).send('Invalid Port');
}
next();
});