diff --git a/Dockerfile.dapper b/Dockerfile.dapper
index 9db096b..c92e563 100644
--- a/Dockerfile.dapper
+++ b/Dockerfile.dapper
@@ -1,18 +1,26 @@
-FROM ubuntu:26.04
+# syntax=docker/dockerfile:1.7
+FROM ubuntu:26.04@sha256:2260313b31c8c011cd2eebe728008efac1b3982be73eb71348ea2648d2c0e09b
 
 ARG DAPPER_HOST_ARCH=amd64
 ARG GO_VERSION=1.27.0
 ARG GO_LINUX_AMD64_SHA256=675c26c449cbb18fc24b74650de1eabbae6e16f64326fd85a283fb3b58280685
-ARG UBUNTU_MIRROR=http://archive.ubuntu.com/ubuntu
+ARG UBUNTU_SNAPSHOT=20260825T000000Z
+
+ADD --checksum=sha256:6077d27c6b6f8b23590cb01ff877ed8c804a67a5442cc32b5a33da10d2bd0e90 \
+    https://snapshot.ubuntu.com/ubuntu/20260825T000000Z/pool/main/c/ca-certificates/ca-certificates_20260601~26.04.1_all.deb \
+    /tmp/ca-certificates.deb
 
 ENV DEBIAN_FRONTEND=noninteractive
 ENV HOST_ARCH=${DAPPER_HOST_ARCH} ARCH=${DAPPER_HOST_ARCH}
 
 RUN set -eux; \
-    find /etc/apt -type f \( -name '*.list' -o -name '*.sources' \) -exec sed -i \
-        -e "s|http://security.ubuntu.com/ubuntu|${UBUNTU_MIRROR}|g" \
-        -e "s|http://archive.ubuntu.com/ubuntu|${UBUNTU_MIRROR}|g" {} +; \
-    printf 'Acquire::Retries "5";\nAcquire::http::Timeout "30";\nAcquire::https::Timeout "30";\nAcquire::http::Pipeline-Depth "0";\n' > /etc/apt/apt.conf.d/80pasturestack-retries; \
+    mkdir -p /tmp/ca-bootstrap /etc/ssl/certs; \
+    dpkg-deb --extract /tmp/ca-certificates.deb /tmp/ca-bootstrap; \
+    find /tmp/ca-bootstrap/usr/share/ca-certificates -type f -name '*.crt' | LC_ALL=C sort | while IFS= read -r certificate; do sed -e '$a\' "${certificate}"; done > /etc/ssl/certs/ca-certificates.crt; \
+    rm -rf /tmp/ca-bootstrap /tmp/ca-certificates.deb; \
+    rm -f /etc/apt/sources.list /etc/apt/sources.list.d/*.list /etc/apt/sources.list.d/*.sources; \
+    printf 'Types: deb\nURIs: https://snapshot.ubuntu.com/ubuntu/%s\nSuites: resolute resolute-updates resolute-backports resolute-security\nComponents: main universe restricted multiverse\nSigned-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg\nSnapshot: no\n' "${UBUNTU_SNAPSHOT}" > /etc/apt/sources.list.d/pasturestack-snapshot.sources; \
+    printf 'Acquire::Retries "5";\nAcquire::http::Timeout "30";\nAcquire::https::Timeout "30";\nAcquire::http::Pipeline-Depth "0";\nAcquire::https::CaInfo "/etc/ssl/certs/ca-certificates.crt";\nAcquire::https::Verify-Peer "true";\nAcquire::https::Verify-Host "true";\nAcquire::AllowInsecureRepositories "false";\nAPT::Get::AllowUnauthenticated "false";\n' > /etc/apt/apt.conf.d/80pasturestack-snapshot; \
     apt-get update && \
     DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
         bash ca-certificates curl file gcc git libc6-dev make tar xz-utils && \
diff --git a/package/Dockerfile b/package/Dockerfile
index df22c70..5a2a62d 100644
--- a/package/Dockerfile
+++ b/package/Dockerfile
@@ -1,16 +1,24 @@
-FROM ubuntu:26.04
+# syntax=docker/dockerfile:1.7
+FROM ubuntu:26.04@sha256:2260313b31c8c011cd2eebe728008efac1b3982be73eb71348ea2648d2c0e09b
 
-ARG UBUNTU_MIRROR=http://archive.ubuntu.com/ubuntu
+ARG UBUNTU_SNAPSHOT=20260825T000000Z
+
+ADD --checksum=sha256:6077d27c6b6f8b23590cb01ff877ed8c804a67a5442cc32b5a33da10d2bd0e90 \
+    https://snapshot.ubuntu.com/ubuntu/20260825T000000Z/pool/main/c/ca-certificates/ca-certificates_20260601~26.04.1_all.deb \
+    /tmp/ca-certificates.deb
 ARG PASTURESTACK_IMAGE_VERSION=dev
 ARG PASTURESTACK_IMAGE_REVISION=unknown
 ARG PASTURESTACK_IMAGE_CREATED=1970-01-01T00:00:00Z
 ENV DEBIAN_FRONTEND=noninteractive
 
 RUN set -eux; \
-    find /etc/apt -type f \( -name '*.list' -o -name '*.sources' \) -exec sed -i \
-        -e "s|http://security.ubuntu.com/ubuntu|${UBUNTU_MIRROR}|g" \
-        -e "s|http://archive.ubuntu.com/ubuntu|${UBUNTU_MIRROR}|g" {} +; \
-    printf 'Acquire::Retries "5";\nAcquire::http::Timeout "30";\nAcquire::https::Timeout "30";\nAcquire::http::Pipeline-Depth "0";\n' > /etc/apt/apt.conf.d/80pasturestack-retries; \
+    mkdir -p /tmp/ca-bootstrap /etc/ssl/certs; \
+    dpkg-deb --extract /tmp/ca-certificates.deb /tmp/ca-bootstrap; \
+    find /tmp/ca-bootstrap/usr/share/ca-certificates -type f -name '*.crt' | LC_ALL=C sort | while IFS= read -r certificate; do sed -e '$a\' "${certificate}"; done > /etc/ssl/certs/ca-certificates.crt; \
+    rm -rf /tmp/ca-bootstrap /tmp/ca-certificates.deb; \
+    rm -f /etc/apt/sources.list /etc/apt/sources.list.d/*.list /etc/apt/sources.list.d/*.sources; \
+    printf 'Types: deb\nURIs: https://snapshot.ubuntu.com/ubuntu/%s\nSuites: resolute resolute-updates resolute-backports resolute-security\nComponents: main universe restricted multiverse\nSigned-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg\nSnapshot: no\n' "${UBUNTU_SNAPSHOT}" > /etc/apt/sources.list.d/pasturestack-snapshot.sources; \
+    printf 'Acquire::Retries "5";\nAcquire::http::Timeout "30";\nAcquire::https::Timeout "30";\nAcquire::http::Pipeline-Depth "0";\nAcquire::https::CaInfo "/etc/ssl/certs/ca-certificates.crt";\nAcquire::https::Verify-Peer "true";\nAcquire::https::Verify-Host "true";\nAcquire::AllowInsecureRepositories "false";\nAPT::Get::AllowUnauthenticated "false";\n' > /etc/apt/apt.conf.d/80pasturestack-snapshot; \
     apt-get update && \
     DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
         bash ca-certificates iproute2 iptables libcap2-bin util-linux && \
diff --git a/package/windows/amd64/Dockerfile b/package/windows/amd64/Dockerfile
index 42a3688..42d0e17 100644
--- a/package/windows/amd64/Dockerfile
+++ b/package/windows/amd64/Dockerfile
@@ -1,5 +1,5 @@
 # escape=`
-FROM mcr.microsoft.com/windows/nanoserver:ltsc2022
+FROM mcr.microsoft.com/windows/nanoserver:ltsc2022@sha256:e4ce8c20390c3785c3cbeef15c579d186b3599d37525c596590cf4508e38d3ff
 
 WORKDIR C:\pasturestack
 COPY metadata-service.exe C:\pasturestack\metadata-service.exe