diff --git a/CHANGELOG.md b/CHANGELOG.md
index 894d03a8c..6e672c94f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -43,6 +43,7 @@ All notable changes to this project will be documented in this file.
 - airflow, druid, hbase, nifi, opensearch-dashboards, superset, trino: Install global npm packages (cdxgen, pnpm, yarn, npm) with `--ignore-scripts`, and only resolve versions that were published at least 7 days ago (`--before`) ([#1682]).
 - superset: Pin npm to `10.9.9` instead of installing the latest version with `nvm install --latest-npm` ([#1682]).
 - opa: update golang to 1.27.1 ([#1697]).
+- spark: Pin pyarrow below 26 to satisfy scikit-learn dependency on NumPy 1.x ([#1695]).
 
 ### Fixed
 
@@ -139,6 +140,7 @@ All notable changes to this project will be documented in this file.
 [#1686]: https://github.com/stackabletech/docker-images/pull/1686
 [#1689]: https://github.com/stackabletech/docker-images/pull/1689
 [#1690]: https://github.com/stackabletech/docker-images/pull/1690
+[#1695]: https://github.com/stackabletech/docker-images/pull/1695
 [#1693]: https://github.com/stackabletech/docker-images/pull/1693
 [#1697]: https://github.com/stackabletech/docker-images/pull/1697
 
diff --git a/spark-connect-client/Dockerfile b/spark-connect-client/Dockerfile
index b7a017eda..86d093812 100644
--- a/spark-connect-client/Dockerfile
+++ b/spark-connect-client/Dockerfile
@@ -41,8 +41,11 @@ USER ${STACKABLE_USER_UID}
 # Packages are intentionally installed in "user mode" to reduce the container attack surface.
 # - pyspark[connect] = spark connect client libs
 # - jupyterlab = notebook client used in demos
+# - pyarrow < 26 = pyarrow 26 requires NumPy >= 2, but scikit-learn 1.3.1 requires
+#   NumPy 1.x. pyarrow does not declare NumPy as a dependency, thus pip cannot detect the conflict.
 RUN pip install --no-cache-dir --user \
   "pyspark[connect]==${PRODUCT_VERSION}" \
+  "pyarrow<26" \
   "jupyterlab==4.4.1" \
   "scikit-learn==1.3.1" \
   "matplotlib==3.10.1"