Rustls contains a vulnerability in its Brotli certificate decompression feature, which is disabled by default. The Brotli decoder accepts an input-specified history window size that can be up to 1 GiB, potentially causing large memory allocations. This can lead to denial of service via memory exhaustion if a malicious peer sends specially crafted Brotli-encoded certificates. Both clients and servers enabling Brotli decompression and client authentication are affected. The issue is fixed in rustls versions 0.23.46 and 0.24.0-dev.2.