CVE-2026-56855

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 Metrics

• v3.1•HIGH•Score: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Trends

Current EPSS score: 0.38%• Percentile: 32%

Techniques & Countermeasures

• CWE-770•Allocation of Resources Without Limits or Throttling

  The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

Affected Systems

• chainguard•aactl

  < 0.4.12-r75

• chainguard•acm-controller

  < 0

• chainguard•acm-controller-fips

  < 0

• chainguard•act

  < 0.2.89-r10

• chainguard•actions-runner-controller

  < 0

• chainguard•actions-runner-controller-fips

  < 0

• chainguard•age

  < 0

• chainguard•age-fips

  < 0

• chainguard•agentbeat

  < 0

• chainguard•agentbeat-fips

  < 0

• chainguard•amass

  < 0

• chainguard•amazon-cloudwatch-agent

  < 0

• chainguard•amazon-cloudwatch-agent-fips

  < 0

• chainguard•amazon-cloudwatch-agent-operator

  < 0

• chainguard•amazon-cloudwatch-agent-operator-fips

  < 0

• chainguard•amazon-ssm-agent

  < 3.3.5226.0-r3

• chainguard•amazon-ssm-agent-ecs-exec

  < 3.3.5226.0-r3

• chainguard•amazon-ssm-agent-ecs-exec-fips

  < 3.3.5226.0-r3

• chainguard•amazon-ssm-agent-fips

  < 3.3.5226.0-r3

• chainguard•apache-exporter

  < 0

• chainguard•apko

  < 1.2.43-r3

• chainguard•apko-fips

  < 1.2.40-r3

• chainguard•apm-server-8.19

  < 0

• chainguard•apm-server-9.2

  < 0

• chainguard•apm-server-9.3

  < 0

• chainguard•apm-server-9.4

  < 0

• chainguard•apm-server-9.5

  < 0

• chainguard•application-gateway-kubernetes-ingress

  < 0

• chainguard•application-gateway-kubernetes-ingress-fips

  < 0

• chainguard•apply-cve-bump

  all | < 0.2.346-r1

• chainguard•argo-cd-3.1

  all

• chainguard•argo-cd-3.1-compat

  all

• chainguard•argo-cd-3.2

  all

• chainguard•argo-cd-3.2-compat

  all

• chainguard•argo-cd-3.3

  < 3.3.14-r8

• chainguard•argo-cd-3.3-compat

  < 3.3.14-r8 | all | < 3.3.14-r9

• chainguard•argo-cd-3.4

  < 3.4.8-r2

• chainguard•argo-cd-3.4-compat

  < 3.4.8-r2

• chainguard•argo-cd-3.5

  < 3.5.2-r4

• chainguard•argo-cd-3.5-compat

  < 3.5.2-r4

• chainguard•argo-cd-fips-3.1

  all

• chainguard•argo-cd-fips-3.1-compat

  all

• chainguard•argo-cd-fips-3.2

  all

• chainguard•argo-cd-fips-3.2-compat

  all

• chainguard•argo-cd-fips-3.3

  < 3.3.14-r7

• chainguard•argo-cd-fips-3.3-compat

  < 3.3.14-r7

• chainguard•argo-cd-fips-3.4

  < 3.4.8-r4

• chainguard•argo-cd-fips-3.4-compat

  < 3.4.8-r4

• chainguard•argo-cd-fips-3.5

  < 3.5.2-r5

• chainguard•argo-cd-fips-3.5-compat

  < 3.5.2-r5

Showing first 50 affected entries in server-rendered view.

References (11)

• https://go.dev/issue/81317
• https://go.dev/cl/826524
• https://groups.google.com/g/golang-announce/c/1y3fb2np35U
• https://pkg.go.dev/vuln/GO-2026-6355
• https://security-tracker.debian.org/tracker/CVE-2026-56855
• https://ubuntu.com/security/CVE-2026-56855
• https://www.cve.org/CVERecord?id=CVE-2026-56855
• https://www.suse.com/security/cve/CVE-2026-56855
• https://pkg.go.dev
• https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56855.json
• https://nvd.nist.gov/vuln/detail/CVE-2026-56855