CVE-2026-16158: high-severity vulnerability in @fastify/reply-from
@fastify/reply-from vulnerable to cross-upstream request routing via URL cache key collision
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.7epss 0.4%
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.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N
Affected products
@fastify/reply-from · @fastify/reply-fromRelated CVEs — @fastify/reply-from
In the same product, most dangerous first.
CVE-2026-117518HIGH@fastify/reply-from vulnerable to path traversal via backslash dot-segment prefix escapeEPSS 0.5%CVE-2026-33805CRITICAL@fastify/reply-from vulnerable to connection header abuse enabling stripping of proxy-added headersEPSS 0.4%CVE-2026-107318HIGH@fastify/reply-from vulnerable to improper certificate validation in built-in HTTPS transportsEPSS 0.1%