CVE-2026-4271

Libsoup is an HTTP library implementation in C. It was originally part of a SOAP (Simple Object Access Protocol) implementation called Soup, but the SOAP and non-SOAP parts have now been split into separate packages.

Security Fix(es):

A flaw was found in libsoup. The HTTP/2 server in libsoup may not fully validate the values of pseudo-headers :scheme, :authority, and :path, which may allow a user to cause a denial of service (DoS).(CVE-2025-32908)

A flaw was identified in the NTLM authentication handling of the libsoup HTTP library, used by GNOME and other applications for network communication. When processing extremely long passwords, an internal size calculation can overflow due to improper use of signed integers. This results in incorrect memory allocation on the stack, followed by unsafe memory copying. As a result, applications using libsoup may crash unexpectedly, creating a denial-of-service risk.(CVE-2026-0719)

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)

A flaw was found in libsoup, an HTTP client/server library. This HTTP Request Smuggling vulnerability arises from non-RFC-compliant parsing in the soup_filter_input_stream_read_line() logic, where libsoup accepts malformed chunk headers, such as lone line feed (LF) characters instead of the required carriage return and line feed (CRLF). A remote attacker can exploit this without authentication or user interaction by sending specially crafted chunked requests. This allows libsoup to parse and process multiple HTTP requests from a single network message, potentially leading to information disclosure.(CVE-2026-1801)

A flaw was identified in libsoup, a widely used HTTP library in GNOME-based systems. When processing specially crafted HTTP Range headers, the library may improperly validate requested byte ranges. In certain build configurations, this could allow a remote attacker to access portions of server memory beyond the intended response. Exploitation requires a vulnerable configuration and access to a server using the embedded SoupServer component.(CVE-2026-2443)

A flaw was found in libsoup, a library for handling HTTP requests. This vulnerability, known as a Use-After-Free, occurs in the HTTP/2 server implementation. A remote attacker can exploit this by sending specially crafted HTTP/2 requests that cause authentication failures. This can lead to the application attempting to access memory that has already been freed, potentially causing application instability or crashes, resulting in a Denial of Service (DoS).(CVE-2026-4271)

Libsoup is an HTTP library implementation in C. It was originally part of a SOAP (Simple Object Access Protocol) implementation called Soup, but the SOAP and non-SOAP parts have now been split into separate packages. libsoup uses the Glib main loop and is designed to work well with GTK applications. This enables GNOME applications to access HTTP servers on the network in a completely asynchronous fashion, very similar to the Gtk+ programming model (a synchronous operation mode is also supported for those who want it), but the SOAP parts were removed long ago.

Security Fix(es):

• libsoup: libsoup: Denial of Service via Use-After-Free in HTTP/2 server (CVE-2026-4271)

• libsoup: libsoup: Information disclosure via cleartext transmission of cookies during HTTPS tunnel establishment (CVE-2026-5119)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Root has patched CVE-2026-4271 in the libsoup3 package for Root:Debian:13. Multiple fixed versions available.

A flaw was found in libsoup, a library for handling HTTP requests. This vulnerability, known as a Use-After-Free, occurs in the HTTP/2 server implementation. A remote attacker can exploit this by sending specially crafted HTTP/2 requests that cause authentication failures. This can lead to the application attempting to access memory that has already been freed, potentially causing application instability or crashes, resulting in a Denial of Service (DoS).

Libsoup is an HTTP library implementation in C. It was originally part of a SOAP (Simple Object Access Protocol) implementation called Soup, but the SOAP and non-SOAP parts have now been split into separate packages. libsoup uses the Glib main loop and is designed to work well with GTK applications. This enables GNOME applications to access HTTP servers on the network in a completely asynchronous fashion, very similar to the Gtk+ programming model (a synchronous operation mode is also supported for those who want it), but the SOAP parts were removed long ago.

Security Fix(es):

• libsoup: libsoup: Denial of Service via Use-After-Free in HTTP/2 server (CVE-2026-4271)
• libsoup: libsoup: Information disclosure via cleartext transmission of cookies during HTTPS tunnel establishment (CVE-2026-5119)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Libsoup is an HTTP library implementation in C. It was originally part of a SOAP (Simple Object Access Protocol) implementation called Soup, but the SOAP and non-SOAP parts have now been split into separate packages. libsoup uses the Glib main loop and is designed to work well with GTK applications. This enables GNOME applications to access HTTP servers on the network in a completely asynchronous fashion, very similar to the Gtk+ programming model (a synchronous operation mode is also supported for those who want it), but the SOAP parts were removed long ago.

Security Fix(es):

• libsoup: libsoup: Denial of Service via Use-After-Free in HTTP/2 server (CVE-2026-4271)
• libsoup: libsoup: Information disclosure via cleartext transmission of cookies during HTTPS tunnel establishment (CVE-2026-5119)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

These are all security issues fixed in the libsoup-3_0-0-3.6.6-5.1 package on the GA media of openSUSE Tumbleweed.

This update for libsoup fixes the following issue

• CVE-2026-4271: use-after-free in the HTTP/2 server when user signal handlers disconnect connections during callback execution (bsc#1259767).

This update for libsoup fixes the following issue

• CVE-2026-4271: use-after-free in the HTTP/2 server when user signal handlers disconnect connections during callback execution (bsc#1259767).

This update for libsoup fixes the following issue

• CVE-2026-4271: use-after-free in the HTTP/2 server when user signal handlers disconnect connections during callback execution (bsc#1259767).

This update for libsoup fixes the following issue

• CVE-2026-4271: use-after-free in the HTTP/2 server when user signal handlers disconnect connections during callback execution (bsc#1259767).

This update for libsoup fixes the following issue

• CVE-2026-4271: use-after-free in the HTTP/2 server when user signal handlers disconnect connections during callback execution (bsc#1259767).

This update for libsoup fixes the following issues

• CVE-2026-1801: HTTP Request Smuggling in soup_filter_input_stream_read_line() (bsc#1257649).
• CVE-2026-4271: use-after-free in the HTTP/2 server when user signal handlers disconnect connections during callback execution (bsc#1259767).

It was discovered that libsoup incorrectly handled certain HTTP/2 requests. A remote attacker could possibly use this issue to cause a denial of service. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-4271)

It was discovered that libsoup incorrectly handled certain HTTPS proxy connections. A remote attacker could possibly use this issue to obtain sensitive information. This issue only affected Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-5119)

It was discovered that libsoup incorrectly parsed certain chunked HTTP requests. A remote attacker could possibly use this issue to bypass security controls. This issue only affected Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-6324)

It was discovered that libsoup incorrectly handled proxy authentication credentials. A remote attacker could possibly use this issue to obtain sensitive information. (CVE-2026-66339)

It was discovered that libsoup incorrectly handled certain HTTP Range headers. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2026-77014, CVE-2026-77680)

It was discovered that libsoup incorrectly handled certain HTTP/2 connections. A remote attacker could possibly use this issue to obtain sensitive information or execute arbitrary code. This issue only affected Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-85197)

It was discovered that libsoup incorrectly handled certain HTTP/2 transfers. A remote attacker could possibly use this issue to cause a denial of service. This issue only affected Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-85534)

USN-8890-1 fixed vulnerabilities in libsoup. This update provides the corresponding updates for libsoup3 on Ubuntu 26.10.

Original advisory details:

It was discovered that libsoup incorrectly handled certain HTTP/2 requests. A remote attacker could possibly use this issue to cause a denial of service. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-4271)

It was discovered that libsoup incorrectly handled certain HTTPS proxy connections. A remote attacker could possibly use this issue to obtain sensitive information. This issue only affected Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-5119)

It was discovered that libsoup incorrectly parsed certain chunked HTTP requests. A remote attacker could possibly use this issue to bypass security controls. This issue only affected Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-6324)

It was discovered that libsoup incorrectly handled proxy authentication credentials. A remote attacker could possibly use this issue to obtain sensitive information. (CVE-2026-66339)

It was discovered that libsoup incorrectly handled certain HTTP Range headers. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2026-77014, CVE-2026-77680)

It was discovered that libsoup incorrectly handled certain HTTP/2 connections. A remote attacker could possibly use this issue to obtain sensitive information or execute arbitrary code. This issue only affected Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-85197)

It was discovered that libsoup incorrectly handled certain HTTP/2 transfers. A remote attacker could possibly use this issue to cause a denial of service. This issue only affected Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-85534)