diff --git a/ci-runner/Dockerfile-v27 b/ci-runner/Dockerfile-v27
index 9eee89368..222220394 100644
--- a/ci-runner/Dockerfile-v27
+++ b/ci-runner/Dockerfile-v27
@@ -24,6 +24,17 @@ RUN apk update && apk add --no-cache --virtual .build-deps && apk add bash && ap
     apk --purge -v del py-pip && \
     rm /var/cache/apk/*
 
+# Ensure /bin/sh reads /etc/shinit for interactive shells
+ENV ENV=/etc/shinit
+
+# Disable core dumps for login shells, bash, and non-login /bin/sh
+RUN set -euo pipefail; \
+    mkdir -p /etc/profile.d; \
+    printf 'ulimit -c 0\n' > /etc/profile.d/disable-core.sh; \
+    printf 'ulimit -c 0\n' > /etc/bash.bashrc; \
+    printf 'ulimit -c 0\n' >> /root/.bashrc; \
+    printf 'ulimit -c 0\n' > /etc/shinit
+
 COPY --from=docker/compose:1.29.2 /usr/local/bin/docker-compose /usr/bin/docker-compose
 
 COPY ./buildpack.json /git-ask-pass.sh /