Affected: AlmaLinux:10: libsoup3, AlmaLinux:10: libsoup3-devel, AlmaLinux:10: libsoup3-doc

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: Heap buffer overflow via uninitialized length in data-URI base64 decoding (CVE-2026-102555) * libsoup: libsoup: Heap buffer overflow from WebSocket Pong signal type confusion (CVE-2026-102556) * libsoup: libsoup: Heap buffer overflow during WebSocket message reassembly (CVE-2026-102557) * libsoup: libsoup: Heap buffer overflow during WebSocket receive-buffer growth (CVE-2026-102558) * libsoup: libsoup: Heap buffer overflow during WebSocket client-frame masking (CVE-2026-102559) * libsoup: libsoup: Heap buffer overflow during outgoing permessage-deflate buffer growth (CVE-2026-102560)

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.

A flaw was found in libsoup. The soup_uri_decode_data_uri() function incorrectly treated base64 data-URI payloads as NUL-terminated strings when calling g_base64_decode_inplace(). If the percent-decoded payload contained embedded NUL bytes, the decoded length could remain uninitialized and be used as the size of the returned GBytes. This can lead to an out-of-bounds read or application crash when processing a crafted data URI.

A flaw was found in libsoup. The soup_uri_decode_data_uri() function incorrectly treated base64 data-URI payloads as NUL-terminated strings when calling g_base64_decode_inplace(). If the percent-decoded payload contained embedded NUL bytes, the decoded length could remain uninitialized and be used as the size of the returned GBytes. This can lead to an out-of-bounds read or application crash when processing a crafted data URI.

libsoup: libsoup: Heap buffer overflow via uninitialized length in data-URI base64 decoding libsoup: libsoup: Heap buffer overflow from WebSocket Pong signal type confusion libsoup: libsoup: Heap buffer overflow during WebSocket message reassembly libsoup: libsoup: Heap buffer overflow during WebSocket receive-buffer growth libsoup: libsoup: Heap buffer overflow during WebSocket client-frame masking libsoup: libsoup: Heap buffer overflow during outgoing permessage-deflate buffer growth

Affected: Ubuntu:Pro:16.04:LTS: libsoup2.4, Ubuntu:Pro:18.04:LTS: libsoup2.4, Ubuntu:Pro:20.04:LTS: libsoup2.4, Ubuntu:22.04:LTS: libsoup2.4, Ubuntu:Pro:22.04:LTS: libsoup3, Ubuntu:24.04:LTS: libsoup2.4, Ubuntu:24.04:LTS: libsoup3, Ubuntu:26.10: libsoup2.4, Ubuntu:26.10: libsoup3, Ubuntu:26.04:LTS: libsoup3 and 1 more

A flaw was found in libsoup. The soup_uri_decode_data_uri() function incorrectly treated base64 data-URI payloads as NUL-terminated strings when calling g_base64_decode_inplace(). If the percent-decoded payload contained embedded NUL bytes, the decoded length could remain uninitialized and be used as the size of the returned GBytes. This can lead to an out-of-bounds read or application crash when processing a crafted data URI.