CVE-2026-120214
@fastify/http-proxy vulnerable to prefix escape via percent-encoded backslash dot-segments
No exploitation reported by the sources we read.
- Published2026-11-02
- WeaknessCWE-22
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
Description
@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.
Timeline
dates in UTC- 2026-11-0210:07CVE publishedCNA
Observed activity
isMalicious corpus · updated 2026-11-02 09:37 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-120214?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-120214?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
Products declared by the CNA
As openjs, the CNA that assigned this CVE, declared them in the CVE record; versions as written. NVD lists no product for this CVE yet: this is the only product data so far.
- @fastify/http-proxyother versions: not affectedAffected
- ≥ 11.6.0, < 11.6.3fixed in 11.6.3semver
Not affected = 11.6.3
Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-11-02
Neither OSV.dev nor the vendor advisories we read list affected versions for CVE-2026-120214 yet.
Fix
No fix published by the sources we read yet. NVD record
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
- Metasploit modules
- none listed Metasploit Framework
Sources
Identifiers
- EUVD-2026-115115same flawENISA EUVD · LicenseRef-ENISA-legal-notice
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
- Published
- 2026-11-02
- Last Modified
- 2026-11-02
- NVD status
- Received
Frequently asked questions
What is CVE-2026-120214?
Is CVE-2026-120214 actively exploited?
What is the CVSS score for CVE-2026-120214?
Hear about the next vulnerability in your software
Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».
No credit card required · No monthly cap on website lookups · 250 API requests/month
Go further
- Following what attackers exploit right now? The CISA KEV additions of the month, with their patch deadlines.
- Running this software? Vulnerability monitoring alerts you to new vulnerabilities in your products.
Related vulnerabilities
Same product first, then the same vendor advisory and the same publication week.