What is CVE-2026-39827?

CVE-2026-39827 is a medium-severity vulnerability in Golang Crypto, classified under Improper Enforcement of Message Integrity During Transmission in a Communication Channel. CVSS score: 6.5/10. Published 2026-05-22.

How severe is CVE-2026-39827?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Vulnerability in Golang Crypto

CVE-2026-39827

An authenticated SSH client that repeatedly opened channels which were rejected by the server caused unbounded memory growth, eventually crashing the server process and affecting all connected users. Rejected channels are now properly removed from the connection's internal state and released for garbage collection.

Published 2026-05-22 · last modified 2026-07-23.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.003 (19.2th percentile), scored 2026-10-19.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 19th percentile — 19.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000

Affected products

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

Weakness classification (CWE)

CWE-924 — Improper Enforcement of Message Integrity During Transmission in a Communication Channel

References

go.dev/issue/35127 (Issue Tracking)
go.dev/cl/781320 (Issue Tracking)
groups.google.com/g/golang-announce/c/a082jnz-LvI (Mailing List)
pkg.go.dev/vuln/GO-2026-5016 (Vendor Advisory)

Frequently asked questions

What is CVE-2026-39827?: CVE-2026-39827 is a medium-severity vulnerability in Golang Crypto, classified under Improper Enforcement of Message Integrity During Transmission in a Communication Channel. CVSS score: 6.5/10. Published 2026-05-22.
How severe is CVE-2026-39827?: Medium severity. CVSS v3 base score is 6.5 out of 10.