Red Hat libsoup Permessage-Deflate Extension inflate allocation of resources

Summaryinfo

A vulnerability was found in Red Hat libsoup and classified as problematic. This issue affects the function inflate of the component Permessage-Deflate Extension. Such manipulation leads to allocation of resources. This vulnerability is listed as CVE-2026-15709. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability was found in Red Hat libsoup (the affected version is unknown). It has been rated as problematic. Affected by this issue is the function inflate of the component Permessage-Deflate Extension. The manipulation with an unknown input leads to a allocation of resources vulnerability. Using CWE to declare the problem leads to CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. Impacted is availability. CVE summarizes:

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).

The advisory is available at access.redhat.com. This vulnerability is handled as CVE-2026-15709 since 07/14/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 07/15/2026). This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

• Red Hat

Name

• libsoup

License

• open-source

Website

• Vendor: https://www.redhat.com/

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