What is CVE-2026-56855?

CVE-2026-56855 is a high-severity vulnerability in Golang Crypto, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-09-02.

How severe is CVE-2026-56855?

High severity. CVSS v3 base score is 7.5 out of 10.

Resource exhaustion in Golang Crypto

CVE-2026-56855

Previously, after a channel has been established, a malicious peer could send crafted messages that would deadlock the entire connection. Now, we handle all RFC 4254 channel messages; global requests are handled explicitly. Then, treat all other messages as a protocol error and tear the connection down instead of buffering and blocking.

Published 2026-09-02 · last modified 2026-09-04.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.005 (41.5th percentile), scored 2026-10-18.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 42nd percentile — 41.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.005 · change: +0.001

Affected products

Weakness classification (CWE)

CWE-770 — Allocation of Resources Without Limits or Throttling

References

go.dev/cl/826524 (Patch)
go.dev/issue/81317 (Issue Tracking, Vendor Advisory)
groups.google.com/g/golang-announce/c/1y3fb2np35U (Mailing List, Vendor Advisory)
pkg.go.dev/vuln/GO-2026-6355 (Vendor Advisory)

Frequently asked questions

What is CVE-2026-56855?: CVE-2026-56855 is a high-severity vulnerability in Golang Crypto, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-09-02.
How severe is CVE-2026-56855?: High severity. CVSS v3 base score is 7.5 out of 10.