Improper Certificate Validation Affecting @fastify/reply-from package, versions <12.7.0
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published13 Oct 2026
- disclosed8 Oct 2026
- creditoss-security-shopify
Introduced: 8 Oct 2026
NewCVE-2026-107318 (opens in a new tab)How to fix?
Upgrade @fastify/reply-from to version 12.7.0 or higher.
Overview
@fastify/reply-from is a forward your HTTP request to another server, for fastify
Affected versions of this package are vulnerable to Improper Certificate Validation via the built-in HTTPS transports (getHttpOpts, getHttp2Opts, and getUndiciOptions in lib/request.js), which unconditionally override rejectUnauthorized to false when the option is absent or partially specified. This disables TLS certificate verification for upstream connections, allowing an attacker positioned between the proxy and the upstream server to perform a MitM attack and intercept or tamper with proxied HTTPS traffic.
Note: This is only exploitable when the upstream target is an HTTPS endpoint, but it affects the default configuration - no non-default options are required to trigger the insecure behaviour.
Workaround
set rejectUnauthorized: true explicitly on the transport in use: undici.tls.rejectUnauthorized, http.requestOptions.rejectUnauthorized, or http2.sessionOptions.rejectUnauthorized.