CVE-2023-34462
MediumCVSS 6.5Exploitation Probability (EPSS)
High risk82th percentile - higher than 82% of all known CVEs
Summary
The vulnerability in `SniHandler` in the Netty framework allows for the allocation of up to 16MB of heap for each channel during the TLS handshake. The lack of proper checks enables the crafting of a packet that can exploit this allocation, potentially leading to resource exhaustion.
Risk Assessment
Organizations may be exposed to DoS attacks that could lead to server memory exhaustion, ultimately affecting service availability.
Recommendation
It is recommended to upgrade to version 4.1.94.Final or later to mitigate this vulnerability.
Original NVD description (English source)
Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. The `SniHandler` can allocate up to 16MB of heap for each channel during the TLS handshake. When the handler or the channel does not have an idle timeout, it can be used to make a TCP server using the `SniHandler` to allocate 16MB of heap. The `SniHandler` class is a handler that waits for the TLS handshake to configure a `SslHandler` according to the indicated server name by the `ClientHello` record. For this matter it allocates a `ByteBuf` using the value defined in the `ClientHello` record. Normally the value of the packet should be smaller than the handshake packet but there are not checks done here and the way the code is written, it is possible to craft a packet that makes the `SslClientHelloHandler`. This vulnerability has been fixed in version 4.1.94.Final.