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Vulnerability record · CVE-2026-56855 · published 2 September 2026

CVE-2026-56855: Golang crypto allocation without limits vulnerability

Golang · Crypto

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.

7.5 CVSS 3.1 High EPSS 0.50% · top 59.6% CWE-770 · Allocation without limits
7.5CVSS 3.1 base score
0.50%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References
4 Sep 2026Last modified by NVD

Description

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.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://go.dev/cl/826524 Patch
https://go.dev/issue/81317 Issue TrackingVendor Advisory
https://groups.google.com/g/golang-announce/c/1y3fb2np35U Mailing ListVendor Advisory
https://pkg.go.dev/vuln/GO-2026-6355 Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-56855), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.