github.com/temporalio/tchannel-go did not validate the one-byte checksum-type field in inbound TChannel call frames. A network peer that can reach a listener can complete the standard initialization handshake and send a call request with an unsupported checksum type. The parser uses that value as an index into a four-entry checksum pool, causing an unrecovered Go panic on the connection read goroutine and terminating the hosting process. This allows remote denial of service against applications that expose the listener to untrusted peers. The impact is limited to availability; no confidentiality or integrity impact was identified.
The CVSS Base score reflects an application that exposes a tchannel-go listener to untrusted network peers without an authenticated transport. The library accepts caller-supplied listeners and dialers, so an embedding application can require mutually authenticated TLS. When client certificates are required and verified, unauthenticated peers are rejected before TChannel frame parsing and the deployment should be assessed using appropriate Environmental metrics.
Restrict TChannel listener access to trusted peers. Where supported by the embedding application, require mutually authenticated TLS so peers without a trusted client certificate are rejected before TChannel frame parsing. External panic-recovery middleware is not a reliable mitigation because the panic occurs on a library-created connection goroutine.
Upgrade github.com/temporalio/tchannel-go to v1.22.1 or later. The fix rejects unsupported checksum types during direct and relay frame parsing and prevents out-of-range checksum-pool access.