CVE-2026-3632 Libsoup: libsoup: http smuggling and server-side request forgery via malformed hostnames
Attackers can exploit hostname validation flaws in libsoup to perform HTTP smuggling and Server-Side Request Forgery, potentially accessing internal systems.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-3632?
CVE-2026-3632 is a low-severity server-side request forgery vulnerability in Redhat Enterprise Linux, published on 17 Mar 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Official description
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.
Weakness: CWE-1286
Which versions are affected by CVE-2026-3632?
It affects 2 products.
Products include Gnome Libsoup, Redhat Enterprise Linux.
How do I fix CVE-2026-3632?
Apply the vendor's patch.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-3632 being exploited?
There is no known exploitation of CVE-2026-3632 in the wild and no public exploit code.
Other vulnerabilities in Redhat Enterprise Linux
- CVE-2026-102556 Libsoup: libsoup: heap buffer overflow from websocket pong signal type confusion
- CVE-2026-102557 Libsoup: libsoup: heap buffer overflow during websocket message reassembly
- CVE-2026-102558 Libsoup: libsoup: heap buffer overflow during websocket receive-buffer growth
- CVE-2026-102559 Libsoup: libsoup: heap buffer overflow during websocket client-frame masking
- CVE-2026-102560 Libsoup: libsoup: heap buffer overflow during outgoing permessage-deflate buffer growth
Sources
Also known as AZL-80229, DEBIAN-CVE-2026-3632, ECHO-cd7e-c6ba-0346, GHSA-v5mp-vx4p-jwp6, UBUNTU-CVE-2026-3632.