CVE-2026-15709 is a vulnerability in Red Hat Enterprise Linux (RHEL)
Published on July 14, 2026
Soupwebsocketextensiondeflate: libsoup: libsoup: websocket permessage-deflate unbounded decompression remote denial of service
A flaw was found in libsoup's WebSocket implementation when using the permessage-deflate extension. The extension's decompression loop (inflate()) processes data in chunks without enforcing an upper boundary limit on the output buffer size. While libsoup limits the incoming compressed frame size via max_incoming_payload_size, it fails to track or limit memory allocation during decompression. A separate check for decompressed size (max_total_message_size) exists but executes only after inflation is complete, and it is entirely disabled by default for client connections. A remote, unauthenticated attacker can exploit this by sending a small, highly compressed payload (a decompression bomb), causing unbounded memory allocation that triggers an Out-of-Memory (OOM) crash and a Denial of Service (DoS).
Vulnerability Analysis
CVE-2026-15709 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.
Timeline
Reported to Red Hat.
Made public.
Weakness Type
What is a Data Amplification Vulnerability?
The software does not handle or incorrectly handles a compressed input with a very high compression ratio that produces a large output. An example of data amplification is a "decompression bomb," a small ZIP file that can produce a large amount of data when it is decompressed.
CVE-2026-15709 has been classified to as a Data Amplification vulnerability or weakness.
Products Associated with CVE-2026-15709
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