Vulnerability record · CVE-2026-16158 · published 18 July 2026
CVE-2026-16158: Fastify\/reply-from vulnerability
Fastify · Fastify\/Reply From
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.
Description
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:L/PR:N/UI:N/S:C/C:H/I:H/A:N
Affected products
1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.
References
| Link | Tags |
|---|---|
| https://cna.openjsf.org/security-advisories.html | Vendor Advisory |
| https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-v574-6498-x57v | Vendor Advisory |
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Related vulnerabilities
Same products first, then exploited flaws of the same weakness class.
Source: NIST National Vulnerability Database (record CVE-2026-16158), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.
