A spoofing issue existed in the handling of URLs. This issue was addressed with improved input validation. This issue is fixed in macOS Big Sur 11.0.1, Safari 14.0.1. Visiting a malicious website may lead to address bar spoofing.

An out-of-bounds read was addressed with improved bounds checking. This issue is fixed in macOS Big Sur 11.0.1, watchOS 7.0, tvOS 14.0, iOS 14.0 and iPadOS 14.0. An application may be able to read restricted memory.

An out-of-bounds read was addressed with improved bounds checking. This issue is fixed in macOS Big Sur 11.0.1, watchOS 7.0, tvOS 14.0, iOS 14.0 and iPadOS 14.0. A malicious application may be able to read restricted memory.

An inconsistent user interface issue was addressed with improved state management. This issue is fixed in macOS Big Sur 11.0.1, Safari 13.1.2. Visiting a malicious website may lead to address bar spoofing.

A path handling issue was addressed with improved validation. This issue is fixed in macOS Big Sur 11.0.1, iOS 14.2 and iPadOS 14.2, tvOS 14.2, watchOS 7.1. A local attacker may be able to elevate their privileges.

A logic issue was addressed with improved state management. This issue is fixed in macOS Big Sur 11.0.1. A sandboxed process may be able to circumvent sandbox restrictions.

A logic issue was addressed with improved state management. This issue is fixed in macOS Big Sur 11.0.1. A malicious application may be able to determine kernel memory layout.

This issue was addressed with improved entitlements. This issue is fixed in macOS Big Sur 11.0.1. A malicious application may be able to access restricted files.

An issue existed within the path validation logic for symlinks. This issue was addressed with improved path sanitization. This issue is fixed in macOS Big Sur 11.0.1, iOS 14.2 and iPadOS 14.2, tvOS 14.2, watchOS 7.1. A local attacker may be able to elevate their privileges.

A logic issue was addressed with improved state management. This issue is fixed in macOS Big Sur 11.0.1, watchOS 7.1, iOS 14.2 and iPadOS 14.2, iCloud for Windows 11.5, tvOS 14.2, iTunes 12.11 for Windows. A local user may be able to read arbitrary files.

Some HTTP/2 implementations are vulnerable to a flood of empty frames, potentially leading to a denial of service. The attacker sends a stream of frames with an empty payload and without the end-of-stream flag. These frames can be DATA, HEADERS, CONTINUATION and/or PUSH_PROMISE. The peer spends time processing each frame disproportionate to attack bandwidth. This can consume excess CPU.

Some HTTP/2 implementations are vulnerable to unconstrained interal data buffering, potentially leading to a denial of service. The attacker opens the HTTP/2 window so the peer can send without constraint; however, they leave the TCP window closed so the peer cannot actually write (many of) the bytes on the wire. The attacker then sends a stream of requests for a large response object. Depending on how the servers queue the responses, this can consume excess memory, CPU, or both.

Some HTTP/2 implementations are vulnerable to a header leak, potentially leading to a denial of service. The attacker sends a stream of headers with a 0-length header name and 0-length header value, optionally Huffman encoded into 1-byte or greater headers. Some implementations allocate memory for these headers and keep the allocation alive until the session dies. This can consume excess memory.

Some HTTP/2 implementations are vulnerable to a settings flood, potentially leading to a denial of service. The attacker sends a stream of SETTINGS frames to the peer. Since the RFC requires that the peer reply with one acknowledgement per SETTINGS frame, an empty SETTINGS frame is almost equivalent in behavior to a ping. Depending on how efficiently this data is queued, this can consume excess CPU, memory, or both.

Some HTTP/2 implementations are vulnerable to a reset flood, potentially leading to a denial of service. The attacker opens a number of streams and sends an invalid request over each stream that should solicit a stream of RST_STREAM frames from the peer. Depending on how the peer queues the RST_STREAM frames, this can consume excess memory, CPU, or both.

Some HTTP/2 implementations are vulnerable to resource loops, potentially leading to a denial of service. The attacker creates multiple request streams and continually shuffles the priority of the streams in a way that causes substantial churn to the priority tree. This can consume excess CPU.

Some HTTP/2 implementations are vulnerable to ping floods, potentially leading to a denial of service. The attacker sends continual pings to an HTTP/2 peer, causing the peer to build an internal queue of responses. Depending on how efficiently this data is queued, this can consume excess CPU, memory, or both.

Some HTTP/2 implementations are vulnerable to window size manipulation and stream prioritization manipulation, potentially leading to a denial of service. The attacker requests a large amount of data from a specified resource over multiple streams. They manipulate window size and stream priority to force the server to queue the data in 1-byte chunks. Depending on how efficiently this data is queued, this can consume excess CPU, memory, or both.

Adobe Acrobat and Reader versions 2018.011.20038 and earlier, 2017.011.30079 and earlier, and 2015.006.30417 and earlier have a Double Free vulnerability. Successful exploitation could lead to arbitrary code execution in the context of the current user.

Low descenders on some Tibetan characters in several fonts on OS X are clipped when rendered in the addressbar. When used as part of an Internationalized Domain Name (IDN) this can be used for domain name spoofing attacks. Note: This attack only affects OS X operating systems. Other operating systems are unaffected. This vulnerability affects Firefox < 58.