CVE-2026-16158
@fastify/reply-from vulnerable to cross-upstream request routing via URL cache key collision
- State
- Published
- Severity
- 8.7 High
- Published
- Jul 18, 2026
- Updated
- Jul 20, 2026
- Reserved
- Jul 17, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 8.7 High | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N | openjs |
Weaknesses
- CWE-441 Unintended Proxy or Intermediary ('Confused Deputy')
Affected Products
| Product | Versions |
|---|---|
@fastify/reply-from@fastify/reply-from |
|
References
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