diff --git a/changelog/unreleased/PR#3106-update-org-eclipse-jdt-ecj.yml b/changelog/unreleased/PR#3106-update-org-eclipse-jdt-ecj.yml
new file mode 100644
index 00000000000..b153241f928
--- /dev/null
+++ b/changelog/unreleased/PR#3106-update-org-eclipse-jdt-ecj.yml
@@ -0,0 +1,7 @@
+title: Update org.eclipse.jdt:ecj to v3.45.0
+type: dependency_update
+authors:
+- name: solrbot
+links:
+- name: PR#3106
+  url: https://github.com/apache/solr/pull/3106
diff --git a/gradle.lockfile b/gradle.lockfile
index c6e6b058c3e..e3bc10c700b 100644
--- a/gradle.lockfile
+++ b/gradle.lockfile
@@ -12,5 +12,5 @@ org.apache.rat:apache-rat-api:0.15=ratDeps
 org.apache.rat:apache-rat-core:0.15=ratDeps
 org.apache.rat:apache-rat-tasks:0.15=ratDeps
 org.apache.rat:apache-rat:0.15=ratDeps
-org.eclipse.jdt:ecj:3.39.0=ecjDeps
+org.eclipse.jdt:ecj:3.45.0=ecjDeps
 empty=
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 7018c17a31e..60834dfc1a5 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -83,7 +83,7 @@ diffplug-spotless = "8.3.0"
 # @keep Use for dockerfile JRE version
 dockerfile-baseimage-java = "25"
 dropwizard-metrics = "4.2.33"
-eclipse-ecj = "3.39.0"
+eclipse-ecj = "3.45.0"
 eclipse-jetty = "12.0.34"
 # @keep jgit version used by git-status.gradle
 eclipse-jgit = "7.6.0.202603022253-r"