CVE-2026-39834

critical

Description

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.

References

https://pkg.go.dev/vuln/GO-2026-5020

https://groups.google.com/g/golang-announce/c/a082jnz-LvI

https://go.dev/issue/79567

https://go.dev/cl/781663

https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-31400

Details

Source: Mitre, NVD

Published: 2026-05-22

Updated: 2026-07-23

Named Vulnerability: GO-2026-5020Named Vulnerability: GHSA-rm3j-f69w-wqmq

Risk Information

CVSS v2

Base Score: 9.4

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:C/A:C

Severity: High

CVSS v3

Base Score: 9.1

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Severity: Critical

EPSS

EPSS: 0.00637