Bug 2528425 (CVE-2026-85197)

Summary: CVE-2026-85197 libsoup: libsoup: Heap use-after-free in libsoup HTTP/2 client on_data_read() via GOAWAY during body upload
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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OS: Linux   
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A flaw was found in libsoup. A malicious HTTP/2 server or a Man-in-the-Middle (MITM) attacker can exploit a heap use-after-free vulnerability in the HTTP/2 client implementation. This occurs when a GNOME application uploads a file using HTTP/2, and the server sends a GOAWAY frame while the file body is being read asynchronously. This can lead to memory corruption, potentially resulting in information disclosure or arbitrary code execution.
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Bug Depends On: 2528508    
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Description OSIDB Bzimport 2026-09-04 07:19:37 UTC 
A heap use-after-free vulnerability exists in libsoup's HTTP/2 client implementation. When a GNOME application sends an HTTP/2 POST request with a file body (using a non-pollable GInputStream such as GFileInputStream), the body data is read asynchronously via g_input_stream_read_async(). If the remote HTTP/2 server sends a GOAWAY frame while this async read is pending, the SoupHTTP2MessageDatastructure is freed through the shutdown path, but the async read callback on_data_read() still fires afterward, accessing the freed heap memory.

This is a remotely-triggerable heap use-after-free — a malicious HTTP/2 server (or MITM attacker) can deterministically trigger it when any GNOME application uploads a file over HTTPS with HTTP/2. Affected applications include GNOME Web (Epiphany), GNOME Software, Flatpak, and any GLib-based application using SoupSession for HTTP/2 file uploads.

Impact type: Heap use-after-free (CWE-416) — the freed 168-byte SoupHTTP2MessageData struct is read after free, and the freed data_source_buffer may also be written to by the still-pending async I/O operation. This constitutes memory corruption with potential for information disclosure or code execution.