OESA-2026-1407

libsoup is an HTTP client/server library for GNOME. It uses GObjects and the glib main loop, to integrate well with GNOME applications, and also has a synchronous API, for use in threaded applications.

Security Fix(es):

A flaw in libsoup’s HTTP header handling allows multiple Host: headers in a request and returns the last occurrence for server-side processing. Common front proxies often honor the first Host: header, so this mismatch can cause vhost confusion where a proxy routes a request to one backend but the backend interprets it as destined for another host. This discrepancy enables request-smuggling style attacks, cache poisoning, or bypassing host-based access controls when an attacker supplies duplicate Host headers.(CVE-2025-14523)

A flaw was found in libsoup’s WebSocket frame processing when handling incoming messages. If a non-default configuration is used where the maximum incoming payload size is unset, the library may read memory outside the intended bounds. This can cause unintended memory exposure or a crash. Applications using libsoup’s WebSocket support with this configuration may be impacted.(CVE-2026-0716)

A flaw was found in libsoup's NTLM (NT LAN Manager) authentication module. When NTLM authentication is enabled, a local attacker can exploit a stack-based buffer overflow vulnerability in the md4sum() function. This allows the attacker to overwrite adjacent memory, which may result in arbitrary code execution with the privileges of the affected application.(CVE-2026-0719)

A flaw was found in libsoup, an HTTP client library. This vulnerability, known as CRLF (Carriage Return Line Feed) Injection, occurs when an HTTP proxy is configured and the library improperly handles URL-decoded input used to create the Host header. A remote attacker can exploit this by providing a specially crafted URL containing CRLF sequences, allowing them to inject additional HTTP headers or complete HTTP request bodies. This can lead to unintended or unauthorized HTTP requests being forwarded by the proxy, potentially impacting downstream services.(CVE-2026-1467)

A flaw was found in the libsoup HTTP library that can cause proxy authentication credentials to be sent to unintended destinations. When handling HTTP redirects, libsoup removes the Authorization header but does not remove the Proxy-Authorization header if the request is redirected to a different host. As a result, sensitive proxy credentials may be leaked to third-party servers. Applications using libsoup for HTTP communication may unintentionally expose proxy authentication data.(CVE-2026-1539)

A flaw was found in libsoup. This stack-based buffer overflow vulnerability occurs during the parsing of multipart HTTP responses due to an incorrect length calculation. A remote attacker can exploit this by sending a specially crafted multipart HTTP response, which can lead to memory corruption. This issue may result in application crashes or arbitrary code execution in applications that process untrusted server responses, and it does not require authentication or user interaction.(CVE-2026-1761)