CVE-2026-16158

HighCVSS 8.7

Published: 18/07/2026(UTC)Updated: 05/08/2026(UTC)Translated: 23/07/2026(UTC)NVD NIST

Exploitation Probability (EPSS)

Low risk

0.23%

14th percentile - higher than 14% of all known CVEs

Summary

Vulnerability in @fastify/reply-from versions 8.3.1 up to but not including 12.6.4. The internal URL cache key is built by concatenating the destination and source path without a delimiter, leading to key collisions and requests being routed to the wrong upstream, enabling cross-upstream data access and modification.

Risk Assessment

An attacker can cause requests intended for one upstream to be handled by another, potentially leading to unauthorized data access and modification.

Recommendation

Update @fastify/reply-from to version 12.6.4. As a workaround, set disableCache: true when registering the plugin.

Other vulnerabilities in @fastify/reply-from

CVE-2026-33805High
A vulnerability in @fastify/reply-from (up to v12.6.1) and @fastify/http-proxy (up to v11.4.3) allows attackers to strip proxy-added headers after they have been added, by manipulating the Connection header. Clients can selectively remove headers used for routing, access control, or security.

Original NVD description (English source)

Impact: @fastify/reply-from versions from 8.3.1 up to but not including 12.6.4 build the internal URL cache key by concatenating the destination and source path without a delimiter. Different destination and source pairs can therefore produce the same key while resolving to different upstream URLs. When getUpstream selects an upstream from request data, a URL cached for one upstream can be reused for a request intended for another upstream, causing cross-upstream data access and modification. The default configuration is affected. Setting disableCache to true prevents the behavior. Patches: upgrade to @fastify/reply-from 12.6.4. Workarounds: pass disableCache: true when registering the plugin.