diff --git a/openai-java-client-okhttp/build.gradle.kts b/openai-java-client-okhttp/build.gradle.kts
index 4d1eb6170..c54e760a6 100644
--- a/openai-java-client-okhttp/build.gradle.kts
+++ b/openai-java-client-okhttp/build.gradle.kts
@@ -11,4 +11,11 @@ dependencies {
     testImplementation(kotlin("test"))
     testImplementation("org.assertj:assertj-core:3.27.7")
     testImplementation("com.github.tomakehurst:wiremock-jre8:2.35.2")
+
+    constraints {
+        // Keep handlebars-helpers at 4.3.1: WireMock 2 links helper classes moved in 4.5.x.
+        testImplementation("com.github.jknack:handlebars:4.5.3") {
+            because("WireMock's transitive 4.3.1 dependency is affected by CVE-2026-55760")
+        }
+    }
 }
diff --git a/openai-java-core/build.gradle.kts b/openai-java-core/build.gradle.kts
index b386f1dbb..9828120db 100644
--- a/openai-java-core/build.gradle.kts
+++ b/openai-java-core/build.gradle.kts
@@ -55,6 +55,13 @@ dependencies {
     testImplementation("org.mockito:mockito-core:5.14.2")
     testImplementation("org.mockito:mockito-junit-jupiter:5.14.2")
     testImplementation("org.mockito.kotlin:mockito-kotlin:4.1.0")
+
+    constraints {
+        // Keep handlebars-helpers at 4.3.1: WireMock 2 links helper classes moved in 4.5.x.
+        testImplementation("com.github.jknack:handlebars:4.5.3") {
+            because("WireMock's transitive 4.3.1 dependency is affected by CVE-2026-55760")
+        }
+    }
 }
 
 // Re-run the compiled tests against the Jackson version consumers receive by default. Service tests
diff --git a/openai-java-core/src/test/kotlin/com/openai/core/WireMockHandlebarsCompatibilityTest.kt b/openai-java-core/src/test/kotlin/com/openai/core/WireMockHandlebarsCompatibilityTest.kt
new file mode 100644
index 000000000..a8c91b644
--- /dev/null
+++ b/openai-java-core/src/test/kotlin/com/openai/core/WireMockHandlebarsCompatibilityTest.kt
@@ -0,0 +1,44 @@
+package com.openai.core
+
+import com.github.tomakehurst.wiremock.WireMockServer
+import com.github.tomakehurst.wiremock.client.WireMock.aResponse
+import com.github.tomakehurst.wiremock.client.WireMock.get
+import com.github.tomakehurst.wiremock.client.WireMock.urlEqualTo
+import com.github.tomakehurst.wiremock.core.WireMockConfiguration.wireMockConfig
+import com.github.tomakehurst.wiremock.extension.responsetemplating.ResponseTemplateTransformer
+import java.net.HttpURLConnection
+import java.net.URL
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+
+internal class WireMockHandlebarsCompatibilityTest {
+
+    @Test
+    fun rendersResponseTemplate() {
+        val server =
+            WireMockServer(
+                wireMockConfig().dynamicPort().extensions(ResponseTemplateTransformer(false))
+            )
+        server.start()
+
+        try {
+            server.stubFor(
+                get(urlEqualTo("/greeting"))
+                    .willReturn(
+                        aResponse()
+                            .withTransformers("response-template")
+                            .withBody("Hello {{request.headers.X-Name}}!")
+                    )
+            )
+
+            val connection =
+                URL("${server.baseUrl()}/greeting").openConnection() as HttpURLConnection
+            connection.setRequestProperty("X-Name", "SDK")
+
+            assertThat(connection.inputStream.bufferedReader().use { it.readText() })
+                .isEqualTo("Hello SDK!")
+        } finally {
+            server.stop()
+        }
+    }
+}