Headline
GHSA-cfgp-2977-2fmm: Connection confusion in gRPC
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/32309
- GitHub Advisory Database
- GitHub Reviewed
- CVE-2023-32731
Connection confusion in gRPC
High severity GitHub Reviewed Published Jul 5, 2023 to the GitHub Advisory Database • Updated Jul 5, 2023
Package
npm @grpc/grpc-js (npm)
Affected versions
< 1.8.8
nuget Grpc.AspNetCore.Server (NuGet)
nuget Grpc.Net.Client (NuGet)
gomod google.golang.org/grpc (Go)
maven io.grpc:grpc-protobuf (Maven)
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 grpc/grpc#32309
References
- https://nvd.nist.gov/vuln/detail/CVE-2023-32731
- grpc/grpc#32309
- grpc/grpc#33005
Published to the GitHub Advisory Database
Jul 5, 2023
Related news
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, so we needed to first buffer up to a 4 gigabyte string before rejecting it as longer than 8 or 16kb. - HPACK varints have an encoding quirk whereby an infinite number of 0’s can be added at the start of an integer. gRPC’s hpack parser needed to read all of them before concluding a parse. - gRPC’s metadata overflow check was performed per frame, so ...