CVE-2026-120214: @fastify/http-proxy vulnerable to prefix escape via percent-encoded backslash dot-segments
Vendor fix available · Affected: @fastify/http-proxy · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 41% of scored CVEs
DescriptionCVE.org
@fastify/http-proxy is a Fastify plugin that proxies HTTP requests to an upstream server under a configured prefix. In versions 11.6.0 through 11.6.2, the destination validation normalizes literal backslashes before it percent-decodes the request path, so a path that encodes its backslashes and dot-segments survives the dot-segment check and is only turned into backslash and double-dot sequences after that check has passed. When the upstream resolves on a platform that treats a backslash as a path separator, the forwarded request walks out of the configured proxy prefix and reaches a sibling location on the upstream. An unauthenticated remote attacker can use this to retrieve upstream resources outside the intended prefix, so the impact is confidentiality only, and exploitation depends on the upstream's path handling. The issue is fixed in @fastify/http-proxy 11.6.3, and users should upgrade to 11.6.3 or later. This is a follow-up to the earlier prefix-escape fix, which did not account for the encoded-backslash form.
Affected products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- @fastify/http-proxy · @fastify/http-proxyfrom 11.6.0 before 11.6.3
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- @fastify/http-proxy
- Published
- November 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-120214 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.