HTTP/2 Rapid reset attack The HTTP/2 protocol allows clients to indicate to the server that a previous stream should be canceled by sending a RSTSTREAM frame. The protocol does not require the client and server to coordinate the cancellation in any way, the client may do it unilaterally. The client may also assume that the cancellation will take effect immediately when the server receives the RSTSTREAM frame, before any other data from that TCP connection is processed.

Abuse of this feature is called a Rapid Reset attack because it relies on the ability for an endpoint to send a RSTSTREAM frame immediately after sending a request frame, which makes the other endpoint start working and then rapidly resets the request. The request is canceled, but leaves the HTTP/2 connection open.

The HTTP/2 Rapid Reset attack built on this capability is simple: The client opens a large number of streams at once as in the standard HTTP/2 attack, but rather than waiting for a response to each request stream from the server or proxy, the client cancels each request immediately.

The ability to reset streams immediately allows each connection to have an indefinite number of requests in flight. By explicitly canceling the requests, the attacker never exceeds the limit on the number of concurrent open streams. The number of in-flight requests is no longer dependent on the round-trip time (RTT), but only on the available network bandwidth.

In a typical HTTP/2 server implementation, the server will still have to do significant amounts of work for canceled requests, such as allocating new stream data structures, parsing the query and doing header decompression, and mapping the URL to a resource. For reverse proxy implementations, the request may be proxied to the backend server before the RSTSTREAM frame is processed. The client on the other hand paid almost no costs for sending the requests. This creates an exploitable cost asymmetry between the server and the client.

Multiple software artifacts implementing HTTP/2 are affected. This advisory was originally ingested from the swift-nio-http2 repo advisory and their original conent follows.

swift-nio-http2 specific advisory swift-nio-http2 is vulnerable to a denial-of-service vulnerability in which a malicious client can create and then reset a large number of HTTP/2 streams in a short period of time. This causes swift-nio-http2 to commit to a large amount of expensive work which it then throws away, including creating entirely new Channels to serve the traffic. This can easily overwhelm an EventLoop and prevent it from making forward progress.

swift-nio-http2 1.28 contains a remediation for this issue that applies reset counter using a sliding window. This constrains the number of stream resets that may occur in a given window of time. Clients violating this limit will have their connections torn down. This allows clients to continue to cancel streams for legitimate reasons, while constraining malicious actors.

Accessibility. A logging issue was addressed with improved data redaction.

A permissions issue was addressed with additional restrictions. This issue is fixed in macOS Sequoia 15.4, macOS Sonoma 14.7.5, macOS Ventura 13.7.5. An app may be able to gain root privileges.

Accessibility. A logging issue was addressed with improved data redaction.

A memory corruption issue was addressed with improved validation. This issue is fixed in iOS 16.7.8 and iPadOS 16.7.8, iOS 17.4 and iPadOS 17.4, macOS Monterey 12.7.6, macOS Sonoma 14.4, macOS Ventura 13.6.7, tvOS 17.4, visionOS 1.1, watchOS 10.4. An attacker with arbitrary kernel read and write capability may be able to bypass kernel memory protections. Apple is aware of a report that this issue may have been exploited.

A memory corruption issue was addressed with improved validation. This issue is fixed in iOS 16.7.6 and iPadOS 16.7.6, iOS 17.4 and iPadOS 17.4, macOS Monterey 12.7.4, macOS Sonoma 14.4, macOS Ventura 13.6.5, tvOS 17.4, visionOS 1.1, watchOS 10.4. An attacker with arbitrary kernel read and write capability may be able to bypass kernel memory protections. Apple is aware of a report that this issue may have been exploited.

A type confusion issue was addressed with improved checks. Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been exploited.

Reference: https://webkitgtk.org/security/WSA-2024-0001.html

Chromium: CVE-2023-5217 Heap buffer overflow in vp8 encoding in libvpx

A buffer overflow issue was addressed with improved memory handling. This issue is fixed in iOS 16.6.1 and iPadOS 16.6.1, macOS Monterey 12.6.9, macOS Ventura 13.5.2, iOS 15.7.9 and iPadOS 15.7.9, macOS Big Sur 11.7.10. Processing a maliciously crafted image may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited.

Chromium: CVE-2023-3079 Type Confusion in V8

Memory corruption in Graphics Linux while assigning shared virtual memory region during IOCTL call.

Memory corruption while submitting a large list of sync points in an AUX command to the IOCTLKGSLGPUAUXCOMMAND.

Memory corruption in DSP Services during a remote call from HLOS to DSP.

A memory corruption issue was addressed with improved state management. This issue is fixed in macOS Ventura 13.3, Safari 16.4, iOS 16.4 and iPadOS 16.4, iOS 15.7.7 and iPadOS 15.7.7. Processing web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited against versions of iOS released before iOS 15.7.

Kernel. An integer overflow was addressed with improved input validation.

A permissions issue was addressed with additional restrictions. This issue is fixed in iOS 18.3 and iPadOS 18.3, macOS Sequoia 15.3, tvOS 18.3, watchOS 11.3. A malicious app may be able to gain root privileges.

A buffer overflow issue was addressed with improved memory handling. This issue is fixed in macOS Sequoia 15.4, macOS Sonoma 14.7.5, macOS Ventura 13.7.5. An app may be able to execute arbitrary code with kernel privileges.

A parsing issue in the handling of directory paths was addressed with improved path validation. This issue is fixed in iOS 18.4 and iPadOS 18.4, macOS Sequoia 15.4, macOS Sonoma 14.7.5, macOS Ventura 13.7.5. An app may be able to gain root privileges.

A validation issue was addressed with improved logic. This issue is fixed in iOS 18.3 and iPadOS 18.3, iPadOS 17.7.4, macOS Sequoia 15.3, macOS Sonoma 14.7.3, tvOS 18.3, visionOS 2.3, watchOS 11.3. An app may be able to execute arbitrary code with kernel privileges.

A type confusion issue was addressed with improved checks. This issue is fixed in iOS 18.3 and iPadOS 18.3, iPadOS 17.7.4, macOS Sequoia 15.3, macOS Sonoma 14.7.3, tvOS 18.3, visionOS 2.3. An attacker on the local network may corrupt process memory.