CVE-2026-39834

Summary

golang.org/x/crypto/ssh vulnerable to infinite loop on large channel writes

Severity

critical

CVSS

9.1

EPSS

0.5% (p43)

CWE

CWE-190

Also known as

GHSA-rm3j-f69w-wqmq, GO-2026-5020

Published

2026-06-25

Updated

2026-06-25

Advisory details

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://github.com/advisories/GHSA-rm3j-f69w-wqmq
• https://nvd.nist.gov/vuln/detail/CVE-2026-39834
• https://go.dev/cl/781663
• https://go.dev/issue/79567
• https://groups.google.com/g/golang-announce/c/a082jnz-LvI
• https://pkg.go.dev/vuln/GO-2026-5020

Related advisories

• CVE-2026-46595 — critical · Go/golang.org/x/crypto/ssh
• CVE-2026-39831 — critical · Go/golang.org/x/crypto/ssh
• CVE-2026-39830 — critical · Go/golang.org/x/crypto/ssh
• CVE-2026-39829 — high · Go/golang.org/x/crypto/ssh
• CVE-2026-46597 — high · Go/golang.org/x/crypto/ssh
• CVE-2026-39827 — medium · Go/golang.org/x/crypto/ssh
• CVE-2026-39835 — medium · Go/golang.org/x/crypto/ssh
• CVE-2026-39828 — medium · Go/golang.org/x/crypto/ssh

Is your project exposed to this? Stateward checks every dependency on every pull request and flags it only if your code actually reaches it.

Summarize with AI

ChatGPTClaudePerplexity