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CVE-2026-16158@fastify/reply-from vulnerable to cross-upstream request routing via URL cache key collision
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.
10.0 CRITICALEPSS 0.38%Not in KEVNVD: Analyzed
Overview
Severity
| Score | Severity | Version | Vector String |
|---|---|---|---|
| 10.0 | CRITICAL | 3.1NVD | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N |
| 8.7 | HIGH | 3.1openjs (CNA) | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N |
Details
- CVE ID
- CVE-2026-16158
- Status
- Analyzed
- Assigner (CNA)
- openjs
- Published
- Jul 18, 2026
- Last modified
- 2026-08-05 19:46 UTC
- Weaknesses
- CWE-441 · Unintended Proxy or Intermediary ('Confused Deputy')
Affected Products
As published by the CNA in the CVE record.
@fastify/reply-from@fastify/reply-from1 version range
- 8.3.1 before 12.6.4