CVE-2026-55603
7.5 · HIGHOverview
CVE-2026-55603 is a high-severity vulnerability affecting chimurai http-proxy-middleware. It was published on June 22, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
http-proxy-middleware is node.js http-proxy middleware. From 3.0.4 until 3.0.7 and 4.1.1, fixRequestBody() is the library's documented helper for re-emitting a request body that was already consumed by a body parser. When the outgoing Content-Type is multipart/form-data, it rebuilds the body with handlerFormDataBodyData(), which interpolates each req.body key and value directly into the multipart wire format without neutralizing CR/LF. A \r\n inside a value (or key) lets an attacker close the current part and inject an entirely new form part. Because the proxy's own body parser saw a single opaque value, any gateway-side policy or validation performed on req.body is evaluated against a different set of fields than the upstream backend ultimately parses a request/parameter desynchronization across the trust boundary. This vulnerability is fixed in 3.0.7 and 4.1.1.
Remediation
Check the references section for vendor advisories and patches from chimurai. Update http-proxy-middleware to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| chimurai | http-proxy-middleware | >= 3.0.4, < 3.0.7 | Affected |
Frequently Asked Questions
What is CVE-2026-55603?
CVE-2026-55603 is a high-severity vulnerability affecting chimurai http-proxy-middleware. It was published on June 22, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
How severe is CVE-2026-55603?
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-55603?
Check the references section for vendor advisories and patches from chimurai. Update http-proxy-middleware to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-55603?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-55603 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
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