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TI-2026-13523 Aliases CVE-2026-16158

@fastify/reply-from vulnerable to cross-upstream request routing via URL cache key collision

Priority MEDIUM 43CWE-441Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · High · None
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00381 32nd percentileScored 2026-11-07
Fix Fixed @fastify/reply-from (@fastify/reply-from): 12.6.4

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
@fastify/reply-from@fastify/reply-from8.3.1 to before 12.6.412.6.4Patch availableCNA
  • @fastify/reply-from Vendor@fastify/reply-from Affected 8.3.1 to before 12.6.4 Fixed in 12.6.4 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:fastify:fastify\/reply-from:*:*:*:*:*:node.js:*:*8.3.1 to before 12.6.4Vulnerablefastify
  • cpe:2.3:a:fastify:fastify\/reply-from:*:*:*:*:*:node.js:*:* Versions 8.3.1 to before 12.6.4 Vulnerable ·fastify

Remediation

  • Fix · CNA @fastify/reply-from (@fastify/reply-from) Fixed in 12.6.4

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-16158
  2. 2026-11-06 Affected versions changed · Red Hat
  3. 2026-11-06 CVSS score added · Red Hat

References

Advisory 2

  • TI-2026-83785 Path traversal in @fastify/reply-from via backslash dot-segments CVSS 3.1HIGH 8.2
  • TI-2026-69753 Improper certificate validation in @fastify/reply-from transports CVSS 3.1HIGH 7.4

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences