Bug 2530594

Summary:	CVE-2026-56855 docker-buildx: golang.org/x/crypto/ssh: Denial of Service via crafted messages [fedora-all]
Product:	[Fedora] Fedora	Reporter:	jkelly <jkelly>
Component:	docker-buildx	Assignee:	Maxwell G <maxwell>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	rawhide	CC:	bradley.g.smith, go-sig, maxwell
Target Milestone:	---	Keywords:	Security, SecurityTracking
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	{"flaws": ["6149aca5-d0d4-472f-b5bb-730faf189259"]}
Fixed In Version:		Doc Type:	---
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	2528050

Description jkelly 2026-09-09 09:13:10 UTC

Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

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.

Comment 1 Brad Smith 2026-09-11 17:22:26 UTC

Confirmed

    {
      "vulnerability": {
        "@id": "https://pkg.go.dev/vuln/GO-2026-6355",
        "name": "GO-2026-6355",
        "description": "Prevent DoS on deadlocked established channel in golang.org/x/crypto/ssh",
        "aliases": [
          "CVE-2026-56855"
        ]
      },
      "products": [
        {
          "@id": "Unknown Product",
          "subcomponents": [
            {
              "@id": "pkg:golang/golang.org%2Fx%2Fcrypto.0"
            }
          ]
        }
      ],
      "status": "affected"
    }
  ]