What is CVE-2026-39834?

CVE-2026-39834 is a critical-severity vulnerability in Golang Crypto, classified under Integer Overflow or Wraparound. CVSS score: 9.1/10. Published 2026-05-22.

How severe is CVE-2026-39834?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Integer overflow in Golang Crypto

CVE-2026-39834

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 co…

Vulnerability class: Integer Overflow

EPSS: 0.001 (17.1th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H.

Affected products

Golang Crypto
Golang.org/x/crypto Golang.org/x/crypto/ssh — versions 0

Weakness classification (CWE)

CWE-190 — Integer Overflow or Wraparound

References

security@golang.org (Issue Tracking)
security@golang.org (Mailing List)
security@golang.org (Issue Tracking)
security@golang.org (Vendor Advisory)

Frequently asked questions

What is CVE-2026-39834?: CVE-2026-39834 is a critical-severity vulnerability in Golang Crypto, classified under Integer Overflow or Wraparound. CVSS score: 9.1/10. Published 2026-05-22.
How severe is CVE-2026-39834?: Critical severity. CVSS v3 base score is 9.1 out of 10.