Medium [CVE-2026-55602] Unintended backend routing due to crafted Host header
This medium-severity Red Hat Linux advisory covers CVE-2026-55602.
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Summary
http-proxy-middleware is node.js http-proxy middleware. 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.
This vulnerability is fixed in 2.0.10, 3.0.6, and 4.1.0. Unanchored substring matching on the attacker-controlled Host header can match a configured host+path key without an exact host match, sending the request to the wrong backend.
Red Hat severity: Moderate — CVSS 6.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N). Weakness: CWE-346.
- < 2.0.10
- < 3.0.6
- < 4.1.0
Official advisory · high-confidence parse· fetched 15 days ago·verify at source
- 2.0.10
- 3.0.6
- 4.1.0
Official advisory · high-confidence parse· fetched 15 days ago·verify at source
Mitigation
Upgrade to a fixed release: 2.0.10, 3.0.6, 4.1.0. That is the remediation for this advisory.
The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.
Official advisory · high-confidence parse· fetched 15 days ago·verify at source
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