CVE-2026-56855
Public on 2026-09-02
Modified on 2026-09-04
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 v3 Base Score
See breakdown
Affected Packages
| Platform | Package | Release Date | Advisory | Status |
|---|---|---|---|---|
| Amazon Linux 2 - Core | amazon-cloudwatch-agent | Pending Fix | ||
| Amazon Linux 2023 | amazon-cloudwatch-agent | Pending Fix | ||
| Amazon Linux 2027 Preview | amazon-cloudwatch-agent | Pending Fix | ||
| Amazon Linux 2 - Aws-nitro-enclaves-cli Extra | amazon-ecr-credential-helper | Not Affected | ||
| Amazon Linux 2 - Docker Extra | amazon-ecr-credential-helper | Not Affected | ||
| Amazon Linux 2 - Ecs Extra | amazon-ecr-credential-helper | Not Affected | ||
| Amazon Linux 2023 | amazon-ecr-credential-helper | Not Affected | ||
| Amazon Linux 2027 Preview | amazon-ecr-credential-helper | Not Affected | ||
| Amazon Linux 2 - Core | amazon-ssm-agent | 2026-10-12 | ALAS2-2026-3969 | Fixed |
| Amazon Linux 2023 | amazon-ssm-agent | 2026-10-12 | ALAS2023-2026-3160 | Fixed |
| Amazon Linux 2027 Preview | amazon-ssm-agent | Pending Fix | ||
| Amazon Linux 2023 | buildah | Pending Fix | ||
| Amazon Linux 2027 Preview | buildah | Pending Fix | ||
| Amazon Linux 2 - Docker Extra | containerd | 2026-10-26 | ALAS2DOCKER-2026-153 | Fixed |
| Amazon Linux 2 - Ecs Extra | containerd | 2026-10-26 | ALAS2ECS-2026-145 | Fixed |
| Amazon Linux 2 - Aws-nitro-enclaves-cli Extra | containerd | 2026-10-26 | ALAS2NITRO-ENCLAVES-2026-125 | Fixed |
| Amazon Linux 2023 | containerd | 2026-10-26 | ALAS2023-2026-3273 | Fixed |
| Amazon Linux 2027 Preview | containerd | 2026-10-26 | ALAS2027-2026-220 | Fixed |
| Amazon Linux 2 - Docker Extra | docker | 2026-10-26 | ALAS2DOCKER-2026-152 | Fixed |
| Amazon Linux 2 - Ecs Extra | docker | 2026-10-26 | ALAS2ECS-2026-148 | Fixed |
| Amazon Linux 2 - Aws-nitro-enclaves-cli Extra | docker | 2026-10-26 | ALAS2NITRO-ENCLAVES-2026-124 | Fixed |
| Amazon Linux 2023 | docker | 2026-10-26 | ALAS2023-2026-3266 | Fixed |
| Amazon Linux 2027 Preview | docker | 2026-10-26 | ALAS2027-2026-237 | Fixed |
| Amazon Linux 2023 | git-lfs | Pending Fix | ||
| Amazon Linux 2027 Preview | git-lfs | Pending Fix | ||
| Amazon Linux 2 - Core | golang | Not Affected | ||
| Amazon Linux 2023 | golang | Not Affected | ||
| Amazon Linux 2027 Preview | golang | Not Affected | ||
| Amazon Linux 2 - Core | nerdctl | 2026-10-26 | ALAS2-2026-4018 | Fixed |
| Amazon Linux 2023 | nerdctl | 2026-10-26 | ALAS2023-2026-3274 | Fixed |
| Amazon Linux 2027 Preview | nerdctl | 2026-10-26 | ALAS2027-2026-221 | Fixed |
| Amazon Linux 2 - Core | rclone | Pending Fix | ||
| Amazon Linux 2023 | rclone | 2026-09-28 | ALAS2023-2026-3129 | Fixed |
| Amazon Linux 2027 Preview | rclone | 2026-09-28 | ALAS2027-2026-105 | Fixed |
| Amazon Linux 2 - Docker Extra | runfinch-finch | 2026-09-28 | ALAS2DOCKER-2026-142 | Fixed |
| Amazon Linux 2023 | runfinch-finch | 2026-09-28 | ALAS2023-2026-3140 | Fixed |
| Amazon Linux 2027 Preview | runfinch-finch | 2026-10-12 | ALAS2027-2026-188 | Fixed |
| Amazon Linux 2023 | skopeo | Pending Fix | ||
| Amazon Linux 2027 Preview | skopeo | Pending Fix |
CVSS Scores
| Score Type | Score | Vector | |
|---|---|---|---|
| Amazon Linux | CVSSv3 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |