CVE-2026-27145
Public on 2026-06-02
Modified on 2026-09-12
Description
(*x509.Certificate).VerifyHostname previously called matchHostnames in a loop over all DNS Subject Alternative Name (SAN) entries. This caused strings.Split(host, ".") to execute repeatedly on the same input hostname. With a large DNS SAN list, verification costs scaled quadratically based on the number of SAN entries multiplied by the hostname's label count. Because x509.Verify validates hostnames before building the certificate chain, this overhead occurred even for untrusted certificates.
CVSS v3 Base Score
See breakdown
Affected Packages
| Platform | Package | Release Date | Advisory | Status |
|---|---|---|---|---|
| Amazon Linux 2 - Core | amazon-cloudwatch-agent | 2026-08-04 | ALAS2-2026-3844 | Fixed |
| Amazon Linux 2023 | amazon-cloudwatch-agent | 2026-08-04 | ALAS2023-2026-2025 | Fixed |
| Amazon Linux 2027 Preview | amazon-cloudwatch-agent | Not Affected | ||
| Amazon Linux 2 - Aws-nitro-enclaves-cli Extra | amazon-ecr-credential-helper | No Fix Planned | ||
| Amazon Linux 2 - Docker Extra | amazon-ecr-credential-helper | No Fix Planned | ||
| Amazon Linux 2 - Ecs Extra | amazon-ecr-credential-helper | No Fix Planned | ||
| Amazon Linux 2023 | amazon-ecr-credential-helper | No Fix Planned | ||
| Amazon Linux 2027 Preview | amazon-ecr-credential-helper | Not Affected | ||
| Amazon Linux 2 - Core | amazon-ssm-agent | No Fix Planned | ||
| Amazon Linux 2023 | amazon-ssm-agent | No Fix Planned | ||
| Amazon Linux 2027 Preview | amazon-ssm-agent | Not Affected | ||
| Amazon Linux 2 - Core | cni-plugins | No Fix Planned | ||
| Amazon Linux 2023 | cni-plugins | No Fix Planned | ||
| Amazon Linux 2027 Preview | cni-plugins | Not Affected | ||
| Amazon Linux 2 - Docker Extra | containerd | 2026-07-08 | ALAS2DOCKER-2026-135 | Fixed |
| Amazon Linux 2 - Ecs Extra | containerd | 2026-07-08 | ALAS2ECS-2026-130 | Fixed |
| Amazon Linux 2 - Aws-nitro-enclaves-cli Extra | containerd | 2026-07-08 | ALAS2NITRO-ENCLAVES-2026-114 | Fixed |
| Amazon Linux 2023 | containerd | 2026-07-07 | ALAS2023-2026-1909 | Fixed |
| Amazon Linux 2027 Preview | containerd | Not Affected | ||
| Amazon Linux 2023 | credentials-fetcher | 2026-06-22 | ALAS2023-2026-1885 | Fixed |
| Amazon Linux 2027 Preview | credentials-fetcher | Not Affected | ||
| Amazon Linux 2 - Core | cri-tools | No Fix Planned | ||
| Amazon Linux 2 - Docker Extra | docker | 2026-07-08 | ALAS2DOCKER-2026-134 | Fixed |
| Amazon Linux 2 - Ecs Extra | docker | 2026-07-08 | ALAS2ECS-2026-131 | Fixed |
| Amazon Linux 2 - Aws-nitro-enclaves-cli Extra | docker | 2026-07-08 | ALAS2NITRO-ENCLAVES-2026-112 | Fixed |
| Amazon Linux 2023 | docker | 2026-07-07 | ALAS2023-2026-1901 | Fixed |
| Amazon Linux 2027 Preview | docker | Not Affected | ||
| Amazon Linux 2 - Ecs Extra | ecs-init | 2026-07-08 | ALAS2ECS-2026-127 | Fixed |
| Amazon Linux 2023 | ecs-init | 2026-07-07 | ALAS2023-2026-1902 | Fixed |
| Amazon Linux 2027 Preview | ecs-init | Not Affected | ||
| Amazon Linux 2023 | git-lfs | No Fix Planned | ||
| Amazon Linux 2027 Preview | git-lfs | Not Affected | ||
| Amazon Linux 2 - Golang1.11 Extra | golang | No Fix Planned | ||
| Amazon Linux 2 - Golang1.19 Extra | golang | No Fix Planned | ||
| Amazon Linux 2 - Golang1.9 Extra | golang | No Fix Planned | ||
| Amazon Linux 2 - Core | golang | 2026-06-22 | ALAS2-2026-3383 | Fixed |
| Amazon Linux 2023 | golang | 2026-06-22 | ALAS2023-2026-1878 | Fixed |
| Amazon Linux 2027 Preview | golang | Not Affected | ||
| Amazon Linux 2023 | golang-github-burntsushi-toml | 2026-06-22 | ALAS2023-2026-1877 | Fixed |
| Amazon Linux 2027 Preview | golang-github-burntsushi-toml | Not Affected | ||
| Amazon Linux 2023 | golang-github-burntsushi-toml-test | 2026-06-22 | ALAS2023-2026-1876 | Fixed |
| Amazon Linux 2027 Preview | golang-github-burntsushi-toml-test | Not Affected | ||
| Amazon Linux 2023 | golang-github-cpuguy83-md2man | 2026-06-22 | ALAS2023-2026-1875 | Fixed |
| Amazon Linux 2027 Preview | golang-github-cpuguy83-md2man | Not Affected | ||
| Amazon Linux 2 - Core | golist | 2026-06-22 | ALAS2-2026-3382 | Fixed |
| Amazon Linux 2023 | golist | 2026-06-22 | ALAS2023-2026-1874 | Fixed |
| Amazon Linux 2027 Preview | golist | Not Affected | ||
| Amazon Linux 2023 | libcap | No Fix Planned | ||
| Amazon Linux 2027 Preview | libcap | Not Affected | ||
| Amazon Linux 2 - Core | nerdctl | 2026-07-08 | ALAS2-2026-3497 | Fixed |
| Amazon Linux 2023 | nerdctl | 2026-07-07 | ALAS2023-2026-1908 | Fixed |
| Amazon Linux 2027 Preview | nerdctl | Not Affected | ||
| Amazon Linux 2 - Aws-nitro-enclaves-cli Extra | oci-add-hooks | No Fix Planned | ||
| Amazon Linux 2 - Docker Extra | oci-add-hooks | No Fix Planned | ||
| Amazon Linux 2 - Ecs Extra | oci-add-hooks | No Fix Planned | ||
| Amazon Linux 2023 | oci-add-hooks | No Fix Planned | ||
| Amazon Linux 2027 Preview | oci-add-hooks | Not Affected | ||
| Amazon Linux 2 - Core | rclone | No Fix Planned | ||
| Amazon Linux 2023 | rclone | No Fix Planned | ||
| Amazon Linux 2027 Preview | rclone | Not Affected | ||
| Amazon Linux 2 - Ecs Extra | runc | No Fix Planned | ||
| Amazon Linux 2 - Docker Extra | runc | 2026-09-14 | ALAS2DOCKER-2026-141 | Fixed |
| Amazon Linux 2 - Aws-nitro-enclaves-cli Extra | runc | 2026-09-14 | ALAS2NITRO-ENCLAVES-2026-119 | Fixed |
| Amazon Linux 2023 | runc | 2026-09-14 | ALAS2023-2026-2138 | Fixed |
| Amazon Linux 2027 Preview | runc | Not Affected | ||
| Amazon Linux 2 - Docker Extra | runfinch-finch | No Fix Planned | ||
| Amazon Linux 2023 | runfinch-finch | No Fix Planned | ||
| Amazon Linux 2027 Preview | runfinch-finch | Not Affected | ||
| Amazon Linux 2 - Docker Extra | soci-snapshotter | 2026-06-22 | ALAS2DOCKER-2026-131 | Fixed |
| Amazon Linux 2023 | soci-snapshotter | 2026-06-22 | ALAS2023-2026-1884 | Fixed |
| Amazon Linux 2027 Preview | soci-snapshotter | Not Affected | ||
| Amazon Linux 2023 | yq | No Fix Planned | ||
| Amazon Linux 2027 Preview | yq | Not Affected |
CVSS Scores
| Score Type | Score | Vector | |
|---|---|---|---|
| Amazon Linux | CVSSv3 | 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |