Distribution advisory
This page covers CVE-2026-55603 as tracked by npm (Root.io), for the package http-proxy-middleware. The fix is available in version 3.0.5-root.io.2; earlier versions remain affected.
How this vulnerability can be exploited
This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is changed, meaning a successful attack can affect components beyond the vulnerable one. Rated impact: confidentiality low, integrity high, availability none. (rating taken from the base CVE record.)
CVSS metrics in full
The score comes from this vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N
- Attack vector: Network — reachable from anywhere that can route to the service.
- Attack complexity: High — the attacker first has to win a race, learn a secret or otherwise prepare the target.
- Privileges required: None — an unauthenticated stranger can try it.
- User interaction: None — nobody has to be tricked into anything.
- Scope: Changed — a successful attack reaches components beyond the vulnerable one.
- Confidentiality impact: Low — limited, and the attacker does not choose what is affected.
- Integrity impact: High — total loss, or loss the attacker controls.
- Availability impact: None.
Weakness class
ROOT-APP-NPM-CVE-2026-55603 is classified as CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection'). The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.
Affected software
ROOT-APP-NPM-CVE-2026-55603 is recorded against 2 packages.
- @rootio/http-proxy-middleware (fixed in 3.0.5-root.io.2)
- http-proxy-middleware (fixed in 3.0.5-aikido.2)
Timeline and source
Published on 27 July 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.
Other advisories for this package
@rootio/http-proxy-middleware has other advisories on record. If you are patching this one, these are worth checking on the same host:
Same weakness in other software
These advisories are the same class of weakness (CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')) in other software:
