Vulnerability in http-proxy-middleware (CVE-2026-55602)
Summary
Vulnerability in http-proxy-middleware (CVE-2026-55602). Data can be tampered with by attackers. Exploitable via router. Mitigation: upgrade to 2.0.10 or later.
Original description
The description as published by the source.
Summary
http-proxy-middleware documents router proxy-table entries as host, path, or host+path selectors, but the host+path implementation uses unanchored substring matching on attacker-controlled request metadata. As a result, a crafted Host header that is only a superstring match for a configured host+path key can still route a request to an unintended backend.
Details
Tested code state:
- validated on tag
v4.0.0-beta.5 - corresponding commit:
339f09ede860197807d4fd99ed9020fa5d0bd358
Relevant code locations:
src/router.tssrc/http-proxy-middleware.ts
Affected public API:
createProxyMiddleware({ router: { 'host/path': 'http://target' } })
Code explanation:
When a proxy-table router key contains /, getTargetFromProxyTable() concatenates attacker-controlled req.headers.host and req.url into a single hostAndPath string, then accepts the route if:
hostAndPath.indexOf(key) > -1
That is a substring test, not an exact host match plus intended path match. In the validated PoC, the configured router key is:
localhost:3000/api
but the attacker-controlled host is:
evillocalhost:3000
and the request path is:
/api
The concatenated attacker-controlled string:
evillocalhost:3000/api
still contains the configured router key as a substring, so the middleware selects the alternate backend even though the host is not equal to the configured host.
Exploit path:
- the application enab…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-55602 has been found in http-proxy-middleware.
Attackers can target a specific entry point like router over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 8.6/10.
What to do: upgrade http-proxy-middleware to 2.0.10 or later.
If unsure, ask your IT team or search "http-proxy-middleware CVE-2026-55602" on the vendor's site.
CVE-2026-55602 (http-proxy-middleware) — CWE-187 / CVSS v3 8.6
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: router / Host / req.headers.host / req.url
Patched: 2.0.10 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-187) exists in http-proxy-middleware. Attackers reach the vulnerable code path via router without authentication.
Check the vendor advisory for the affected versions of http-proxy-middleware. Attack surface: router / Host / req.headers.host / req.url.
Severity: High (CVSS 8.6/10). Data can be tampered with by attackers.
Update to 2.0.10.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'http-proxy-middleware' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'http-proxy-middleware' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
http-proxy-middlewareを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade http-proxy-middleware to 2.0.10ステージング環境で 2.0.10 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- package github.com
- web github.com
- web github.com