CVE-2026-39834: Golang Crypto

Critical severity, CVSS 9.1. EPSS: 0.6% chance of exploitation in the next 30 days.

When writing data larger than 4GB in a single Write call on an SSH channel, an integer overflow in the internal payload size calculation caused the write loop to spin indefinitely, sending empty packets without making progress. The size comparison now uses int64 to prevent truncation.

Affected products

• Golang Crypto: before 0.52.0 (fixed in 0.52.0)

Published 2026-05-22. Last modified 2026-07-23.