diff --git a/build-logic/src/main/kotlin/velocity.java-conventions.gradle.kts b/build-logic/src/main/kotlin/velocity.java-conventions.gradle.kts
index ac46453..bd49f44 100644
--- a/build-logic/src/main/kotlin/velocity.java-conventions.gradle.kts
+++ b/build-logic/src/main/kotlin/velocity.java-conventions.gradle.kts
@@ -21,6 +21,29 @@ java {
 dependencies {
     compileOnly(libs.jspecify)
     errorprone(libs.build.errorprone.core)
+
+    // --- Transitive security floors (Dependabot alerts) ---------------------------------------
+    // None of these are direct dependencies; they arrive transitively (Netty via Lettuce,
+    // Jackson 2.x + logback via Dropwizard, commons-compress via Testcontainers, rhino via
+    // swagger-parser). We raise each to its first patched release as a *floor*, not a pin:
+    //   - `platform(...)` imports a BOM as constraints, aligning a whole artifact family (Netty's
+    //     ~9 modules, Jackson 2.x's ~12) to one version so we never split e.g. netty-handler 4.2.15
+    //     against netty-buffer 4.2.13.
+    //   - the `constraints { }` block floors the standalone coordinates.
+    // Floor semantics mean a higher version reached by any other path still wins, so these never
+    // block a future upgrade; Dependabot bumps the catalog entries on its weekly gradle run.
+    // Declared on `implementation` so they reach runtimeClasspath and (via testImplementation
+    // extendsFrom implementation) the test classpaths where rhino/commons-compress live. Modules
+    // that don't pull a given artifact are unaffected — an unused constraint is a no-op.
+    implementation(platform(libs.netty.bom))
+    implementation(platform(libs.jackson2.bom))
+    constraints {
+        implementation(libs.logback.core) { because("logback-core object-injection advisory") }
+        implementation(libs.logback.classic) { because("keep logback-classic aligned with logback-core floor") }
+        implementation(libs.commons.compress) { because("commons-compress Pack200/DUMP DoS advisories") }
+        implementation(libs.commons.lang3) { because("commons-lang3 uncontrolled-recursion advisory") }
+        implementation(libs.rhino) { because("rhino toFixed() DoS advisory") }
+    }
 }
 
 tasks.withType<JavaCompile>().configureEach {
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 65bfa32..3d032a6 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -58,6 +58,18 @@ assertj = "3.27.7"
 mockito = "5.23.0"
 logback = "1.5.38"
 
+# Security floors for transitive dependencies (see the "Transitive security floors" block in
+# velocity.java-conventions). None of these are direct dependencies of ours — they arrive
+# transitively (Netty via Lettuce, Jackson 2.x/logback via Dropwizard, commons-compress via
+# Testcontainers, rhino via swagger-parser). Each value is the first patched release for the
+# corresponding Dependabot advisory; it is applied as a *floor*, not a pin, so a higher version
+# on any resolution path still wins. Dependabot keeps these current on its weekly gradle run.
+netty = "4.2.15.Final"          # netty-handler / netty-resolver-dns advisories (GHSA, high)
+jackson2 = "2.21.5"             # jackson-databind 2.x case-insensitive @JsonIgnoreProperties bypass
+commons-compress = "1.26.0"     # Pack200 OOM + corrupted-DUMP infinite-loop DoS
+commons-lang3 = "3.18.0"        # uncontrolled recursion on long inputs
+rhino = "1.7.14.1"              # toFixed() high-CPU DoS
+
 [libraries]
 jspecify = { module = "org.jspecify:jspecify", version.ref = "jspecify" }
 
@@ -114,6 +126,16 @@ mockito-core = { module = "org.mockito:mockito-core", version.ref = "mockito" }
 mockito-junit-jupiter = { module = "org.mockito:mockito-junit-jupiter", version.ref = "mockito" }
 logback-classic = { module = "ch.qos.logback:logback-classic", version.ref = "logback" }
 
+# Transitive security floors — referenced only by the constraints block in
+# velocity.java-conventions, never depended on directly. BOMs (netty, jackson 2.x) align a whole
+# artifact family to one version; the singletons floor one coordinate each.
+netty-bom = { module = "io.netty:netty-bom", version.ref = "netty" }
+jackson2-bom = { module = "com.fasterxml.jackson:jackson-bom", version.ref = "jackson2" }
+logback-core = { module = "ch.qos.logback:logback-core", version.ref = "logback" }
+commons-compress = { module = "org.apache.commons:commons-compress", version.ref = "commons-compress" }
+commons-lang3 = { module = "org.apache.commons:commons-lang3", version.ref = "commons-lang3" }
+rhino = { module = "org.mozilla:rhino", version.ref = "rhino" }
+
 [bundles]
 test = ["junit-jupiter", "assertj-core", "mockito-core", "mockito-junit-jupiter"]
 jackson = ["jackson-databind", "jackson-annotations"]