diff --git a/CHANGELOG.md b/CHANGELOG.md
index b1728374..1e70b51a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 ### Chore & Maintenance
 
 - Update `jackson-databind`, `jackson-core`, and `jackson-annotations` dependencies to the 2.21 LTS line due to vulnerability
+- Update `jackson-databind` and `jackson-core` to 2.21.7 to fix CVE-2026-91776
 - Update `lf-api-client-core` dependency to 2.2.5
 
 ## 1.0.3
diff --git a/pom.xml b/pom.xml
index d9b472b8..c523a127 100644
--- a/pom.xml
+++ b/pom.xml
@@ -309,7 +309,7 @@
     <maven.compiler.target>${java.version}</maven.compiler.target>
     <gson-fire-version>1.8.0</gson-fire-version>
     <swagger-core-version>2.0.0</swagger-core-version>
-    <jackson-version>2.21.6</jackson-version>
+    <jackson-version>2.21.7</jackson-version>
     <jackson-annotations-version>2.21</jackson-annotations-version>
     <retrofit-version>2.9.0</retrofit-version>
     <threetenbp-version>1.3.5</threetenbp-version>
diff --git a/src/test/java/com/laserfiche/repository/api/unit/EntryDeserializationTest.java b/src/test/java/com/laserfiche/repository/api/unit/EntryDeserializationTest.java
new file mode 100644
index 00000000..03260ae5
--- /dev/null
+++ b/src/test/java/com/laserfiche/repository/api/unit/EntryDeserializationTest.java
@@ -0,0 +1,100 @@
+// Copyright (c) Laserfiche.
+// Licensed under the MIT License. See LICENSE in the project root for license information.
+package com.laserfiche.repository.api.unit;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.deser.impl.TypeWrappedDeserializer;
+import com.fasterxml.jackson.databind.jsontype.impl.TypeDeserializerBase;
+import com.laserfiche.api.client.deserialization.TokenClientObjectMapper;
+import com.laserfiche.repository.api.clients.impl.model.Document;
+import com.laserfiche.repository.api.clients.impl.model.Entry;
+import com.laserfiche.repository.api.clients.impl.model.EntryType;
+import com.laserfiche.repository.api.clients.impl.model.Folder;
+import com.laserfiche.repository.api.clients.impl.model.RecordSeries;
+import com.laserfiche.repository.api.clients.impl.model.Shortcut;
+import java.lang.reflect.Field;
+import java.util.Arrays;
+import java.util.Map;
+import org.junit.jupiter.api.Test;
+
+public class EntryDeserializationTest {
+    @Test
+    void readEntry_RepeatedUnknownTypeUsesFallback() throws ReflectiveOperationException {
+        TokenClientObjectMapper mapper = new TokenClientObjectMapper();
+        for (int i = 0; i < 10000; i++) {
+            assertFallback(mapper, "unknown");
+        }
+        assertEquals(1, typeIdCache(mapper).size());
+    }
+
+    @Test
+    void readEntry_DistinctUnknownTypesHaveBoundedCache() throws ReflectiveOperationException {
+        TokenClientObjectMapper mapper = new TokenClientObjectMapper();
+        for (int i = 0; i < 10000; i++) {
+            assertFallback(mapper, "unknown-" + i);
+        }
+        Map<?, ?> cache = typeIdCache(mapper);
+        assertTrue(cache.size() > 0);
+        assertTrue(cache.size() <= 1000, "Unknown type IDs must not grow the cache beyond Jackson's bound");
+        Entry folder = mapper.readValue("{\"entryType\":\"Folder\",\"id\":42}", Entry.class);
+        assertEquals(Folder.class, folder.getClass());
+        assertEquals(EntryType.FOLDER, folder.getEntryType());
+    }
+
+    @Test
+    void readEntry_OverlongUnknownTypesAreNotCached() throws ReflectiveOperationException {
+        TokenClientObjectMapper mapper = new TokenClientObjectMapper();
+        char[] characters = new char[257];
+        Arrays.fill(characters, 'x');
+        String prefix = new String(characters);
+        for (int i = 0; i < 100; i++) {
+            assertFallback(mapper, prefix + i);
+        }
+        assertEquals(0, typeIdCache(mapper).size());
+    }
+
+    @Test
+    void readEntry_KnownTypesStillSelectTheirSubtypes() {
+        TokenClientObjectMapper mapper = new TokenClientObjectMapper();
+        assertKnownType(mapper, EntryType.DOCUMENT, Document.class);
+        assertKnownType(mapper, EntryType.FOLDER, Folder.class);
+        assertKnownType(mapper, EntryType.SHORTCUT, Shortcut.class);
+        assertKnownType(mapper, EntryType.RECORD_SERIES, RecordSeries.class);
+    }
+
+    private static void assertFallback(TokenClientObjectMapper mapper, String typeId) {
+        Entry entry = mapper.readValue("{\"entryType\":\"" + typeId + "\",\"id\":42}", Entry.class);
+        assertEquals(Entry.class, entry.getClass());
+        assertNull(entry.getEntryType());
+        assertEquals(Integer.valueOf(42), entry.getId());
+    }
+
+    private static void assertKnownType(
+            TokenClientObjectMapper mapper, EntryType entryType, Class<? extends Entry> subtype) {
+        Entry entry = mapper.readValue("{\"entryType\":\"" + entryType.getValue() + "\",\"id\":42}", Entry.class);
+        assertEquals(subtype, entry.getClass());
+        assertEquals(entryType, entry.getEntryType());
+        assertEquals(Integer.valueOf(42), entry.getId());
+    }
+
+    private static Map<?, ?> typeIdCache(TokenClientObjectMapper mapper) throws ReflectiveOperationException {
+        // Observe retained keys on the actual mapper; successful fallback reads alone cannot detect this regression.
+        Field mapperField = TokenClientObjectMapper.class.getDeclaredField("jacksonMapper");
+        mapperField.setAccessible(true);
+        ObjectMapper jackson = ObjectMapper.class.cast(mapperField.get(mapper));
+        Field rootsField = ObjectMapper.class.getDeclaredField("_rootDeserializers");
+        rootsField.setAccessible(true);
+        Map<?, ?> roots = Map.class.cast(rootsField.get(jackson));
+        TypeWrappedDeserializer root =
+                TypeWrappedDeserializer.class.cast(roots.get(jackson.constructType(Entry.class)));
+        Field typeField = TypeWrappedDeserializer.class.getDeclaredField("_typeDeserializer");
+        typeField.setAccessible(true);
+        Field cacheField = TypeDeserializerBase.class.getDeclaredField("_deserializers");
+        cacheField.setAccessible(true);
+        return Map.class.cast(cacheField.get(typeField.get(root)));
+    }
+}