Check all ancestor namespace transitions when rendering raw text in html in golang.org/x/net
In childTextNodesAreLiteral, walking up the tree previously stopped at the nearest foreign ancestor once an HTML integration point was found. However, that integration point may itself be a descendant of an element that was foster-parented into a foreign namespace (such as <mglyph> or <malignmark> fostered under <mtext>), causing a parser to resolve the subtree in a different foreign namespace upon re-parsing the rendered output. Continue walking the full ancestor chain and verify that every transition from a non-empty namespace occurs at an HTML integration point before emitting literal text.
Avoid quadratic complexity when coalescing text nodes in html in golang.org/x/net
When coalescing adjacent text nodes in addText and fosterParent, appending to an existing TextNode's Data via string concatenation (n.Data += text) reallocated and copied the accumulated string on every token. Inputs containing many short text runs separated by ignored end tags (such as "a</x>") caused O(n^2) allocations and byte copies. Accumulate coalesced text in per-node byte slices during parsing and materialize Data strings once at the end of parse.
HTTP/2 server crash due to HPACK encoder race in net/http
HTTP/2 servers could end up crashing due to inadvertently modifying its HPACK encoder concurrently. This happens because the server modifies the HPACK encoder from two goroutines without synchronization: one uses the encoder to encode a HEADERS frame as part of a response sent to a client and the other modifies the encoder's table size when handling a SETTINGS frame containing SETTINGS_HEADER_TABLE_SIZE that a client sends. A malicious client can repeatedly send a request while changing the header table size to crash the server.
Double flow control refund on HTTP/2 server streams in net/http
The HTTP/2 server can refund connection-level flow control twice for the same data: Once when a client resets a stream (refunding data for any sent-but-unread portion of the stream), and again when a request handler reads the buffered data. A malicious client can exploit this to bypass the configured connection-level flow control limit (MaxReceiveBufferPerConnection). Total buffered data is still limited by the concurrent stream limit and stream-level flow control.
Excessive CPU consumption from repeated initial window changes in net/http
A malicious HTTP/2 peer can cause excessive CPU consumption in the client or server by opening a large number of streams and then sending many small SETTINGS frames containing SETTINGS_INITIAL_WINDOW_SIZE values.
HTTP/2 transport accepts malformed framing-related headers in net/http
Historically, we have been rather lax about malformed framing-related headers in our HTTP/2 implementation, as they cannot interfere with HTTP/2 framing. However, this makes it possible for our HTTP/2 implementation to forward responses containing such headers to an HTTP/1 client when acting as a reverse proxy. If the HTTP/1 client also does not behave strictly enough, this can result in response smuggling.
HTTP/2 server memory exhaustion due to Trailer headers in net/http
When "Trailer" headers are sent by a client, the HTTP server internally uses the header values to populate the Request.Trailer map passed to the server handler. Because Request.Trailer is a map, each entry incurs memory overhead. For HTTP/2 servers, a malicious client can exploit this by sending a "Trailer" header that declares a large number of fields, causing the server to allocate a disproportionate amount of memory while bypassing Server.MaxHeaderValueCount and Server.MaxHeaderBytes limits. This exploit is not applicable for HTTP/1 servers, which do not support multiplexing a large number of requests over one TCP connection, and whose Ser
Invoking duplicate attributes can cause XSS in golang.org/x/net/html
Parsing arbitrary HTML which is then rendered using Render can result in an unexpected HTML tree. This can be leveraged to execute XSS attacks in applications that attempt to sanitize input HTML before rendering.
Invoking incorrect handling of character references in DOCTYPE nodes in golang.org/x/net/html
Parsing arbitrary HTML which is then rendered using Render can result in an unexpected HTML tree. This can be leveraged to execute XSS attacks in applications that attempt to sanitize input HTML before rendering.
Invoking incorrect handling of HTML elements in foreign content in golang.org/x/net/html
Parsing arbitrary HTML which is then rendered using Render can result in an unexpected HTML tree. This can be leveraged to execute XSS attacks in applications that attempt to sanitize input HTML before rendering.
Invoking failure to reject ASCII-only Punycode-encoded labels in golang.org/x/net/idna
The ToASCII and ToUnicode functions incorrectly accept Punycode-encoded labels that decode to an ASCII-only label. For example, ToUnicode("xn--example-.com") incorrectly returns the name "example.com" rather than an error. This behavior can lead to privilege escalation in programs using the idna package. For example, a program which performs privilege checks on the ASCII hostname may reject "example.com" but permit "xn--example-.com". If that program subsequently converts the ASCII hostname to Unicode, it will inadvertently permits access to the Unicode name "example.com".
Invoking incorrect handling of namespaced elements in foreign content in golang.org/x/net/html
Parsing arbitrary HTML which is then rendered using Render can result in an unexpected HTML tree. This can be leveraged to execute XSS attacks in applications that attempt to sanitize input HTML before rendering.
Infinite loop in HTTP/2 transport when given bad SETTINGS_MAX_FRAME_SIZE in net/http/internal/http2 in golang.org/x/net
When processing HTTP/2 SETTINGS frames, transport will enter an infinite loop of writing CONTINUATION frames if it receives a SETTINGS_MAX_FRAME_SIZE with a value of 0.
The html.Parse function in golang.org/x/net/html has an infinite parsing loop when processing certain inputs, which can lead to denial of service (DoS) if an attacker provides specially crafted HTML content.
Quadratic parsing complexity in golang.org/x/net/html
The html.Parse function in golang.org/x/net/html has quadratic parsing complexity when processing certain inputs, which can lead to denial of service (DoS) if an attacker provides specially crafted HTML content.
Incorrect Neutralization of Input During Web Page Generation in x/net in golang.org/x/net
The tokenizer incorrectly interprets tags with unquoted attribute values that end with a solidus character (/) as self-closing. When directly using Tokenizer, this can result in such tags incorrectly being marked as self-closing, and when using the Parse functions, this can result in content following such tags as being placed in the wrong scope during DOM construction, but only when tags are in foreign content (e.g. <math>, <svg>, etc contexts).
Non-linear parsing of case-insensitive content in golang.org/x/net/html
An attacker can craft an input to the Parse functions that would be processed non-linearly with respect to its length, resulting in extremely slow parsing. This could cause a denial of service.
An attacker may cause an HTTP/2 endpoint to read arbitrary amounts of header data by sending an excessive number of CONTINUATION frames. Maintaining HPACK state requires parsing and processing all HEADERS and CONTINUATION frames on a connection. When a request's headers exceed MaxHeaderBytes, no memory is allocated to store the excess headers, but they are still parsed. This permits an attacker to cause an HTTP/2 endpoint to read arbitrary amounts of header data, all associated with a request which is going to be rejected. These headers can include Huffman-encoded data which is significantly more expensive for the receiver to decode than for
Improper rendering of text nodes in golang.org/x/net/html
Text nodes not in the HTML namespace are incorrectly literally rendered, causing text which should be escaped to not be. This could lead to an XSS attack.