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PatchSiren cyber security CVE debrief

CVE-2026-107318 @fastify/reply-from CVE debrief

The @fastify/reply-from plugin for Fastify is vulnerable to improper certificate validation in its built-in HTTPS transports. This issue allows an on-path network attacker to impersonate the configured HTTPS upstream, potentially leading to unauthorized access to sensitive information. The vulnerability is fixed in version 12.7.0 and later. Affected product deployments should be identified in managed environments, and owners should be assigned for follow-up. The official advisory or CVE record should be reviewed to validate affected scope, severity, and vendor guidance. Users should plan for vendor-supported updates or mitigations through normal change control where exposure is is

Vendor
@fastify/reply-from
Product
Unknown
CVSS
HIGH 7.4
CISA KEV
Not listed in stored evidence
Original CVE published
2026-10-08
Original CVE updated
2026-10-09
Advisory published
2026-10-08
Advisory updated
2026-10-09

Who should care

Fastify users who utilize the @fastify/reply-from plugin, especially those who forward requests to HTTPS upstreams, should assess their exposure and upgrade to version 12.7.0 or later.

Why it matters

The @fastify/reply-from plugin's improper certificate validation in built-in HTTPS transports allows an on-path network attacker to impersonate the configured HTTPS upstream, potentially leading to unauthorized access to sensitive information. Fastify users who utilize this plugin, especially those forwarding requests to HTTPS upstreams, should assess their exposure and upgrade to version 12.7.0 or later.

  • Potential unauthorized access to sensitive information
  • Impersonation of the configured HTTPS upstream
  • Forgery of responses trusted by the application

Technical summary

The @fastify/reply-from plugin for Fastify is vulnerable to improper certificate validation in its built-in HTTPS transports. This issue allows an on-path network attacker to impersonate the configured HTTPS upstream, potentially leading to unauthorized access to sensitive information. The vulnerability is fixed in version 12.7.0 and later. Affected product context includes Fastify users who utilize the @fastify/reply-from plugin, especially those who forward requests to HTTPS upstreams. The defensive impact is high, and source-grounded technical framing indicates that users should assess their exposure and upgrade to version 12.7.0 or later.

Defensive priority

High

Recommended defensive actions

  • Upgrade to version 12.7.0 or later of the @fastify/reply-from plugin
  • Implement explicit rejectUnauthorized true on the transport
  • Supply an already configured undici instance
  • Use the undici global agent
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
  • Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
  • Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed

Evidence notes

The CVE record and source item provide details on the vulnerability, including its impact and fix. However, additional information from other sources may be necessary to fully assess the vulnerability.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-107318 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-107318

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-107318 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-107318

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.