libsoup Hostname Validation Flaw Enabling HTTP Smuggling & SSRF
CVE-2026-3632 Published on March 17, 2026
Libsoup: libsoup: http smuggling and server-side request forgery via malformed hostnames
A flaw was found in libsoup, a library used by applications to send network requests. This vulnerability occurs because libsoup does not properly validate hostnames, allowing special characters to be injected into HTTP headers. A remote attacker could exploit this to perform HTTP smuggling, where they can send hidden, malicious requests alongside legitimate ones. In certain situations, this could lead to Server-Side Request Forgery (SSRF), enabling an attacker to force the server to make unauthorized requests to other internal or external systems. The impact is low, as SoupServer is not actually used in internet infrastructure.
Vulnerability Analysis
CVE-2026-3632 is exploitable with network access, requires user interaction and user privileges. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to be low. considered to have a small impact on confidentiality and integrity and availability.
Timeline
Reported to Red Hat.
Made public.
Weakness Type
Improper Validation of Syntactic Correctness of Input
The product receives input that is expected to be well-formed - i.e., to comply with a certain syntax - but it does not validate or incorrectly validates that the input complies with the syntax.
Products Associated with CVE-2026-3632
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