DISPUTED In OpenResty through 1.13.6.1, URI parameters are obtained using the ngx.req.geturiargs and ngx.req.getpostargs functions that ignore parameters beyond the hundredth one, which might allow remote attackers to bypass intended access restrictions or interfere with certain Web Application Firewall (ngxluawaf or X-WAF) products. NOTE: the vendor has reported that 100 parameters is an intentional default setting, but is adjustable within the API. The vendor's position is that a security-relevant misuse of the API by a WAF product is a vulnerability in the WAF product, not a vulnerability in OpenResty.

A flaw was found in nginx. An off-by-one error while processing DNS responses allows a network attacker to write a dot character out of bounds in a heap allocated buffer which can allow overwriting the least significant byte of next heap chunk metadata likely leading to a remote code execution in certain circumstances. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

An issue in OpenResty lua-nginx-module v.0.10.26 and before allows a remote attacker to conduct HTTP request smuggling via a crafted HEAD request.

OpenResty is a high performance web platform. From 1.29.2.1 to before 1.29.2.5, an out-of-bounds write vulnerability exists in the upstream PROXY protocol v2 implementation. When OpenResty is configured to send PROXY protocol version 2 headers to upstream servers, constructing the header in the stream proxy protocol v2 patch can write beyond the bounds of the allocated buffer, causing the worker process to crash and resulting in a denial of service. Only configurations that explicitly enable PROXY protocol v2 for upstream connections are impacted. This issue is fixed in version 1.29.2.5.

An issue was discovered in OpenResty before 1.15.8.4. ngxhttpluasubrequest.c allows HTTP request smuggling, as demonstrated by the ngx.location.capture API.

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.

Malcolm is a network traffic analysis tool suite. Prior to version 26.07.0, role-based access control enforced in the Nginx OpenResty Lua layer evaluates the raw, unnormalized ngx.var.requesturi, while Nginx itself routes requests using the normalized path. An authenticated low-privilege user can prepend a traversal segment (for example /x/../upload/...) so that Nginx routes the request to a restricted backend while the Lua role check fails to match any rule and falls open, granting access it should deny. Version 26.07.0 fixes the issue.

In ljstrhash.c in OpenResty 1.19.3.1 through 1.25.3.1, the string hashing function (used during string interning) allows HashDoS (Hash Denial of Service) attacks. An attacker could cause excessive resource usage during proxy operations via crafted requests, potentially leading to a denial of service with relatively few incoming requests. This vulnerability only exists in the OpenResty fork in the openresty/luajit2 GitHub repository. The LuaJIT/LuaJIT repository. is unaffected.

Last updated 24 July 2024