Bug 2454489 (CVE-2026-32762)

Summary:	CVE-2026-32762 rack: Rack: Parameter smuggling via improper Forwarded header parsing
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	akostadi, amasferr, crizzo, dmayorov, eshamard, jlledo, jvasik, kaycoth, pantinor, rblanco, tsedmik
Target Milestone:	---	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in Rack, a modular Ruby web server interface. This vulnerability arises from improper parsing of the RFC 7239 Forwarded header, where semicolons within quoted values are incorrectly interpreted as delimiters. An attacker can exploit this by crafting a malicious Forwarded header, potentially leading to the smuggling of host, protocol, or other parameters. This could allow for spoofing or bypassing security measures in deployments utilizing upstream proxies, Web Application Firewalls (WAFs), or other intermediaries.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-04-02 18:01:46 UTC

Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21 and 3.2.0 to before 3.2.6, Rack::Utils.forwarded_values parses the RFC 7239 Forwarded header by splitting on semicolons before handling quoted-string values. Because quoted values may legally contain semicolons, a header can be interpreted by Rack as multiple Forwarded directives rather than as a single quoted for value. In deployments where an upstream proxy, WAF, or intermediary validates or preserves quoted Forwarded values differently, this discrepancy can allow an attacker to smuggle host, proto, for, or by parameters through a single header value. This issue has been patched in versions 3.1.21 and 3.2.6.