diff --git a/ops/pipeline/build-cpu-arm64.sh b/ops/pipeline/build-cpu-arm64.sh
index e3e0cebb22c8..c52777ffdef7 100755
--- a/ops/pipeline/build-cpu-arm64.sh
+++ b/ops/pipeline/build-cpu-arm64.sh
@@ -13,7 +13,7 @@ source ops/pipeline/classify-git-branch.sh
 source ops/pipeline/get-docker-registry-details.sh
 
 WHEEL_TAG=manylinux_2_28_aarch64
-IMAGE_URI=${DOCKER_REGISTRY_URL}/xgb-ci.aarch64:main
+IMAGE_URI=${DOCKER_REGISTRY_URL}/xgb-ci.aarch64:PR-6
 
 echo "--- Build CPU code targeting ARM64"
 set -x
diff --git a/ops/pipeline/build-cpu.sh b/ops/pipeline/build-cpu.sh
index 2443006bd7c2..637546d9ccdd 100755
--- a/ops/pipeline/build-cpu.sh
+++ b/ops/pipeline/build-cpu.sh
@@ -6,7 +6,7 @@ set -euo pipefail
 source ops/pipeline/classify-git-branch.sh
 source ops/pipeline/get-docker-registry-details.sh
 
-IMAGE_URI=${DOCKER_REGISTRY_URL}/xgb-ci.cpu:main
+IMAGE_URI=${DOCKER_REGISTRY_URL}/xgb-ci.cpu:PR-6
 
 echo "--- Build CPU code"
 set -x
diff --git a/ops/pipeline/build-cuda.sh b/ops/pipeline/build-cuda.sh
index a34a0dcc7c28..0f8220e0d93b 100755
--- a/ops/pipeline/build-cuda.sh
+++ b/ops/pipeline/build-cuda.sh
@@ -35,8 +35,8 @@ source ops/pipeline/classify-git-branch.sh
 source ops/pipeline/get-docker-registry-details.sh
 
 WHEEL_TAG=manylinux_2_28_x86_64
-BUILD_IMAGE_URI="${DOCKER_REGISTRY_URL}/${image_repo}:main"
-MANYLINUX_IMAGE_URI="${DOCKER_REGISTRY_URL}/xgb-ci.${WHEEL_TAG}:main"
+BUILD_IMAGE_URI="${DOCKER_REGISTRY_URL}/${image_repo}:PR-6"
+MANYLINUX_IMAGE_URI="${DOCKER_REGISTRY_URL}/xgb-ci.${WHEEL_TAG}:PR-6"
 
 echo "--- Build with CUDA"
 
diff --git a/ops/pipeline/build-gpu-rpkg.sh b/ops/pipeline/build-gpu-rpkg.sh
index ced68245d4bf..8860ced3121e 100755
--- a/ops/pipeline/build-gpu-rpkg.sh
+++ b/ops/pipeline/build-gpu-rpkg.sh
@@ -11,7 +11,7 @@ fi
 source ops/pipeline/classify-git-branch.sh
 source ops/pipeline/get-docker-registry-details.sh
 
-IMAGE_URI=${DOCKER_REGISTRY_URL}/xgb-ci.gpu_build_r_rockylinux8:main
+IMAGE_URI=${DOCKER_REGISTRY_URL}/xgb-ci.gpu_build_r_rockylinux8:PR-6
 
 echo "--- Build XGBoost R package with CUDA"
 set -x
diff --git a/ops/pipeline/build-jvm-doc.sh b/ops/pipeline/build-jvm-doc.sh
index 3f9fad3bc2d0..a383fc37cc10 100755
--- a/ops/pipeline/build-jvm-doc.sh
+++ b/ops/pipeline/build-jvm-doc.sh
@@ -19,7 +19,7 @@ fi
 
 source ops/pipeline/get-docker-registry-details.sh
 
-IMAGE_URI=${DOCKER_REGISTRY_URL}/xgb-ci.jvm_gpu_build:main
+IMAGE_URI=${DOCKER_REGISTRY_URL}/xgb-ci.jvm_gpu_build:PR-6
 
 echo "--- Build JVM packages doc"
 set -x
diff --git a/ops/pipeline/build-jvm-gpu.sh b/ops/pipeline/build-jvm-gpu.sh
index 2f71849efb3b..8812bdece95d 100755
--- a/ops/pipeline/build-jvm-gpu.sh
+++ b/ops/pipeline/build-jvm-gpu.sh
@@ -6,7 +6,7 @@ set -euo pipefail
 source ops/pipeline/classify-git-branch.sh
 source ops/pipeline/get-docker-registry-details.sh
 
-IMAGE_URI=${DOCKER_REGISTRY_URL}/xgb-ci.jvm_gpu_build:main
+IMAGE_URI=${DOCKER_REGISTRY_URL}/xgb-ci.jvm_gpu_build:PR-6
 
 echo "--- Build libxgboost4j.so with CUDA"
 
diff --git a/ops/pipeline/build-jvm-manylinux2014.sh b/ops/pipeline/build-jvm-manylinux2014.sh
index 5b3942fb67ef..5cea3973fa48 100755
--- a/ops/pipeline/build-jvm-manylinux2014.sh
+++ b/ops/pipeline/build-jvm-manylinux2014.sh
@@ -15,7 +15,7 @@ image_repo="xgb-ci.manylinux2014_${arch}"
 source ops/pipeline/classify-git-branch.sh
 source ops/pipeline/get-docker-registry-details.sh
 
-IMAGE_URI="${DOCKER_REGISTRY_URL}/${image_repo}:main"
+IMAGE_URI="${DOCKER_REGISTRY_URL}/${image_repo}:PR-6"
 
 # Build XGBoost4J binary
 echo "--- Build libxgboost4j.so (targeting glibc 2.17)"
diff --git a/ops/pipeline/build-manylinux2014.sh b/ops/pipeline/build-manylinux2014.sh
index cf8ca7a94da3..73de518e3ea4 100755
--- a/ops/pipeline/build-manylinux2014.sh
+++ b/ops/pipeline/build-manylinux2014.sh
@@ -21,7 +21,7 @@ source ops/pipeline/get-docker-registry-details.sh
 
 WHEEL_TAG="manylinux2014_${arch}"
 IMAGE_REPO="xgb-ci.${WHEEL_TAG}"
-IMAGE_URI="${DOCKER_REGISTRY_URL}/${IMAGE_REPO}:main"
+IMAGE_URI="${DOCKER_REGISTRY_URL}/${IMAGE_REPO}:PR-6"
 PYTHON_BIN="/opt/python/cp310-cp310/bin/python"
 
 echo "--- Build binary wheel for ${WHEEL_TAG}"
diff --git a/ops/pipeline/build-test-jvm-packages.sh b/ops/pipeline/build-test-jvm-packages.sh
index 5c1f5e8b0d4a..7ffcd00aaaf8 100755
--- a/ops/pipeline/build-test-jvm-packages.sh
+++ b/ops/pipeline/build-test-jvm-packages.sh
@@ -23,7 +23,7 @@ do
   fi
 done
 
-IMAGE_URI=${DOCKER_REGISTRY_URL}/xgb-ci.jvm:main
+IMAGE_URI=${DOCKER_REGISTRY_URL}/xgb-ci.jvm:PR-6
 
 set -x
 
diff --git a/ops/pipeline/deploy-jvm-packages.sh b/ops/pipeline/deploy-jvm-packages.sh
index d73b289b165d..ee9969c1d4f0 100755
--- a/ops/pipeline/deploy-jvm-packages.sh
+++ b/ops/pipeline/deploy-jvm-packages.sh
@@ -16,7 +16,7 @@ variant="$1"
 image_repo="$2"
 scala_version="$3"
 
-IMAGE_URI="${DOCKER_REGISTRY_URL}/${image_repo}:main"
+IMAGE_URI="${DOCKER_REGISTRY_URL}/${image_repo}:PR-6"
 
 set -x
 
diff --git a/ops/pipeline/run-clang-tidy.sh b/ops/pipeline/run-clang-tidy.sh
index c6166e99cb33..39693e9e2c65 100755
--- a/ops/pipeline/run-clang-tidy.sh
+++ b/ops/pipeline/run-clang-tidy.sh
@@ -4,7 +4,7 @@ set -euo pipefail
 
 source ops/pipeline/get-docker-registry-details.sh
 
-IMAGE_URI=${DOCKER_REGISTRY_URL}/xgb-ci.clang_tidy:main
+IMAGE_URI=${DOCKER_REGISTRY_URL}/xgb-ci.clang_tidy:PR-6
 
 echo "--- Run clang-tidy"
 set -x
diff --git a/ops/pipeline/test-cpp-gpu.sh b/ops/pipeline/test-cpp-gpu.sh
index 4262ebda7268..cd809f6a27a6 100755
--- a/ops/pipeline/test-cpp-gpu.sh
+++ b/ops/pipeline/test-cpp-gpu.sh
@@ -11,7 +11,7 @@ suite=$1
 
 source ops/pipeline/get-docker-registry-details.sh
 
-IMAGE_URI=${DOCKER_REGISTRY_URL}/xgb-ci.gpu:main
+IMAGE_URI=${DOCKER_REGISTRY_URL}/xgb-ci.gpu:PR-6
 
 case "${suite}" in
   gpu)
diff --git a/ops/pipeline/test-cpp-i386.sh b/ops/pipeline/test-cpp-i386.sh
index dd7827ff2de9..46246c4153db 100755
--- a/ops/pipeline/test-cpp-i386.sh
+++ b/ops/pipeline/test-cpp-i386.sh
@@ -5,7 +5,7 @@ set -euo pipefail
 
 source ops/pipeline/get-docker-registry-details.sh
 
-IMAGE_URI="${DOCKER_REGISTRY_URL}/xgb-ci.i386:main"
+IMAGE_URI="${DOCKER_REGISTRY_URL}/xgb-ci.i386:PR-6"
 
 set -x
 python3 ops/docker_run.py \
diff --git a/ops/pipeline/test-jvm-gpu.sh b/ops/pipeline/test-jvm-gpu.sh
index c7dfdd05b43f..21ebe86c8d54 100755
--- a/ops/pipeline/test-jvm-gpu.sh
+++ b/ops/pipeline/test-jvm-gpu.sh
@@ -25,7 +25,7 @@ done
 
 source ops/pipeline/get-docker-registry-details.sh
 
-IMAGE_URI=${DOCKER_REGISTRY_URL}/xgb-ci.jvm_gpu_build:main
+IMAGE_URI=${DOCKER_REGISTRY_URL}/xgb-ci.jvm_gpu_build:PR-6
 
 set -x
 
diff --git a/ops/pipeline/test-python-wheel.sh b/ops/pipeline/test-python-wheel.sh
index 5551870e0b77..4a403c93179f 100755
--- a/ops/pipeline/test-python-wheel.sh
+++ b/ops/pipeline/test-python-wheel.sh
@@ -20,7 +20,7 @@ else
 fi
 
 source ops/pipeline/get-docker-registry-details.sh
-IMAGE_URI="${DOCKER_REGISTRY_URL}/${image_repo}:main"
+IMAGE_URI="${DOCKER_REGISTRY_URL}/${image_repo}:PR-6"
 
 set -x
 python3 ops/docker_run.py --image-uri "${IMAGE_URI}" ${gpu_option} \