CVE-2026-88829

Busybox: busybox: http request smuggling via pipelined requests in httpd reverse proxy

Published Oct 14, 2026 CVSS 3.1 · 7.2 High EPSS < 1% KEV · Not listed
Description
A flaw was found in BusyBox httpd's reverse proxy feature. When the proxy is configured to forward requests matching a URL prefix to a backend server, only the first HTTP request on a TCP connection has its path rewritten. An attacker can send a pipelined second request that is relayed verbatim to the backend, bypassing the configured path restrictions. This allows accessing arbitrary paths on the backend server that were not intended to be exposed through the proxy.

Remediation

Vendor Workaround

Do not use BusyBox httpd P: rules as the sole path-based access control in front of sensitive backends. Remove P: lines if proxying is not required, or place a full reverse proxy (for example nginx or HAProxy) in front of the backend. Recompile with FEATURE_HTTPD_PROXY disabled if the applet is not needed.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Busybox
Busybox busybox
Redhat hardened Images
Vendors & Products Busybox
Busybox busybox
Redhat hardened Images
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description A flaw was found in BusyBox httpd's reverse proxy feature. When the proxy is configured to forward requests matching a URL prefix to a backend server, only the first HTTP request on a TCP connection has its path rewritten. An attacker can send a pipelined second request that is relayed verbatim to the backend, bypassing the configured path restrictions. This allows accessing arbitrary paths on the backend server that were not intended to be exposed through the proxy.
Title Busybox: busybox: http request smuggling via pipelined requests in httpd reverse proxy
First Time appeared Redhat
Redhat hummingbird
Weaknesses CWE-444
CPEs cpe:/a:redhat:hummingbird:1
Vendors & Products Redhat
Redhat hummingbird
References
Metrics cvssV3_1

{'score': 7.2, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
redhat
Published
Updated
Nov 11, 2026, 8:27 PM
Reserved
Sep 10, 2026, 9:42 AM
Status
Awaiting Analysis
Published
Oct 14, 2026, 10:17 AM
Modified
Oct 15, 2026, 4:33 PM
Severity
Moderate
Public date
Oct 14, 2026, 8:00 AM