Lack of error handling in the TCP server in Google's gRPC starting version 1.23 on posix-compatible platforms (ex. Linux) allows an attacker to cause a denial of service by initiating a significant number of connections with the server. Note that gRPC C++ Python, and Ruby are affected, but gRPC Java, and Go are NOT affected.
gRPC contains a vulnerability that allows hpack table accounting errors could lead to unwanted disconnects between clients and servers in exceptional cases/ Three vectors were found that allow the following DOS attacks:
- Unbounded memory buffering in the HPACK parser
- Unbounded CPU consumption in the HPACK parser
The unbounded CPU consumption is down to a copy that occurred per-input-block in the parser, and because that could be unbounded due to the memory copy bug we end up with an O(n^2) parsing loop, with n selected by the client.
The unbounded memory buffering bugs:
- The header size limit check was behind the string reading code,
When gRPC HTTP2 stack raised a header size exceeded error, it skipped parsing the rest of the HPACK frame. This caused any HPACK table mutations to also be skipped, resulting in a desynchronization of HPACK tables between sender and receiver. If leveraged, say, between a proxy and a backend, this could lead to requests from the proxy being interpreted as containing headers from different proxy clients - leading to an information leak that can be used for privilege escalation or data exfiltration. We recommend upgrading beyond the commit contained in https://github.com/grpc/grpc/pull/33005 https://github.com/grpc/grpc/pull/33005
gRPC contains a vulnerability whereby a client can cause a termination of connection between a HTTP2 proxy and a gRPC server: a base64 encoding error for `-bin` suffixed headers will result in a disconnection by the gRPC server, but is typically allowed by HTTP2 proxies. We recommend upgrading beyond the commit in https://github.com/grpc/grpc/pull/32309 https://www.google.com/url
There exists an vulnerability causing an abort() to be called in gRPC.
The following headers cause gRPC's C++ implementation to abort() when called via http2:
te: x (x != trailers)
:scheme: x (x != http, https)
grpclb_client_stats: x (x == anything)
On top of sending one of those headers, a later header must be sent that gets the total header size past 8KB. We recommend upgrading past git commit 2485fa94bd8a723e5c977d55a3ce10b301b437f8 or v1.53 and above.
Google gRPC before 2017-03-29 has an out-of-bounds write caused by a heap-based use-after-free related to the grpc_call_destroy function in core/lib/surface/call.c.