Medium [CVE-2026-15712] HTTP/2 GOAWAY frame parsing heap buffer over-read via invalid NUL-termination assumption

A heap buffer over-read vulnerability was discovered in libsoup's (versions: libsoup 3.0 to 3.7.0) HTTP/2 connection tracking framework. When the library processes an HTTP/2 GOAWAY frame, it improperly handles the "Additional Debug Data" payload by assuming the data stream is a safely NUL-terminated C-string.

Because the parser lacks strict length-boundary verification before reading this data, a remote, unauthenticated attacker can intentionally send a malformed GOAWAY frame missing the appropriate null delimiter.

This causes the library to read past the end of the allocated buffer, triggering an application crash that results in a denial of service (DoS), or potentially exposing fragments of memory contents.

This vulnerability poses a moderate impact to system confidentiality and availability for software implementations leveraging libsoup for HTTP/2 client or server communications. An unauthenticated network adversary can manipulate frame characteristics to force memory parsing out-of-bounds without requiring special system privileges or user interaction.

While primarily resulting in a denial of service via a segmentation fault, the risk of data exposure from adjacent heap allocations places this as a notable security boundary failure within the protocol decoding stack. Red Hat severity: Low — CVSS 5.9 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H).

Weakness: CWE-125.