# CVE-2026-65652: Temporal tchannel-go checksum-type validation bypass

Source: https://junglewise.ai/threats/cve-2026-65652-github-com-temporalio-tchannel-go-did-not-validate-the-one-byte  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-21. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-65652 · Severity: info · Published 2026-09-21

Temporal's tchannel-go library, used for RPC communication, fails to validate the checksum algorithm type in incoming requests. An attacker on the network can send a malformed request with an invalid checksum type, causing the library to crash and terminate the entire process. This results in a denial of service against any application using this library to accept remote connections.

Vendors: [Temporal](https://junglewise.ai/threats/vendors/temporal).

## Quick answers

**Is CVE-2026-65652 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-65652 being exploited in the wild.

**How severe is CVE-2026-65652?** Informational severity, published 21 September 2026.

**Which products and versions are affected?** Temporal Tchannel-Go prior to fix.

**Is there a fix for CVE-2026-65652?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-65652 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-65652?** Check whether you run Temporal Tchannel-Go at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is an out-of-bounds array access in the checksum validation logic. The one-byte checksum-type field in inbound TChannel call frames is used directly as an index into a four-entry checksum pool without bounds checking. An unauthenticated network peer can complete the TChannel handshake and send a call request with an unsupported checksum type value (outside 0–3), causing an unrecovered Go panic in the connection read goroutine and process termination.

## Affected products

- Temporal tchannel-go prior to fix

## Timeline

- 2026-09-21: disclosed

## References

- [https://pkg.go.dev/](https://pkg.go.dev/)
- [https://github.com/temporalio/tchannel-go/blob/8706a1ab5f617efd79dace7ab2d1d80cc1881df0/checksum.go](https://github.com/temporalio/tchannel-go/blob/8706a1ab5f617efd79dace7ab2d1d80cc1881df0/checksum.go)

## Related threats

- [Temporal tchannel-go denial of service in fragment parsing](https://junglewise.ai/threats/cve-2026-65653-github-com-temporalio-tchannel-go-did-not-reject-tchannel-call)