High 7.5Published Sep 2, 2026

CVE-2026-56855Prevent DoS on deadlocked established channel in golang.org/x/crypto/ssh

Updated under an hour ago (2026-10-19 07:30 UTC)

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It affects golang.org/x/crypto/ssh and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for golang.org/x/crypto/ssh

Exploited in the last 30 days

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: 7.5 HIGH (v3.1, CISA ADP)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-770
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Go
NVD analysis: Analyzed
Record last updated: Sep 3, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

golang.org/x/crypto golang.org/x/crypto/ssh golang.org_x_crypto:ssh (from the name)	before 0.56.0	CNA record
golang crypto golang:crypto	before 0.56.0	NVD

References

https://go.dev/issue/81317issue-tracking, vendor-advisory
https://go.dev/cl/826524patch
https://groups.google.com/g/golang-announce/c/1y3fb2np35Umailing-list, vendor-advisory
https://pkg.go.dev/vuln/GO-2026-6355vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.