diff --git a/core/src/main/java/org/apache/shiro/realm/activedirectory/ActiveDirectoryRealm.java b/core/src/main/java/org/apache/shiro/realm/activedirectory/ActiveDirectoryRealm.java
index 3dc459cb33..1a58c2941a 100644
--- a/core/src/main/java/org/apache/shiro/realm/activedirectory/ActiveDirectoryRealm.java
+++ b/core/src/main/java/org/apache/shiro/realm/activedirectory/ActiveDirectoryRealm.java
@@ -39,6 +39,7 @@
 import javax.naming.directory.SearchControls;
 import javax.naming.directory.SearchResult;
 import javax.naming.ldap.LdapContext;
+import javax.naming.ldap.Rdn;
 import java.util.*;
 
 
@@ -162,7 +163,7 @@ protected Set<String> getRoleNamesForUser(String username, LdapContext ldapConte
         SearchControls searchCtls = new SearchControls();
         searchCtls.setSearchScope(SearchControls.SUBTREE_SCOPE);
 
-        String userPrincipalName = username;
+        String userPrincipalName = Rdn.escapeValue(username);
         if (principalSuffix != null && !userPrincipalName.toLowerCase(Locale.ROOT).endsWith(principalSuffix.toLowerCase(Locale.ROOT))) {
             userPrincipalName += principalSuffix;
         }
diff --git a/core/src/main/java/org/apache/shiro/realm/ldap/DefaultLdapRealm.java b/core/src/main/java/org/apache/shiro/realm/ldap/DefaultLdapRealm.java
index dec43a94d2..62ae56f106 100644
--- a/core/src/main/java/org/apache/shiro/realm/ldap/DefaultLdapRealm.java
+++ b/core/src/main/java/org/apache/shiro/realm/ldap/DefaultLdapRealm.java
@@ -35,6 +35,7 @@
 import javax.naming.AuthenticationNotSupportedException;
 import javax.naming.NamingException;
 import javax.naming.ldap.LdapContext;
+import javax.naming.ldap.Rdn;
 
 /**
  * An LDAP {@link org.apache.shiro.realm.Realm Realm} implementation utilizing Sun's/Oracle's
@@ -239,11 +240,12 @@ protected String getUserDn(String principal) throws IllegalArgumentException, Il
 
         int prefixLength = prefix != null ? prefix.length() : 0;
         int suffixLength = suffix != null ? suffix.length() : 0;
-        StringBuilder sb = new StringBuilder(prefixLength + principal.length() + suffixLength);
+        String sanitizedPrincipal = Rdn.escapeValue(principal);
+        StringBuilder sb = new StringBuilder(prefixLength + sanitizedPrincipal.length() + suffixLength);
         if (prefixLength > 0) {
             sb.append(prefix);
         }
-        sb.append(principal);
+        sb.append(sanitizedPrincipal);
         if (suffixLength > 0) {
             sb.append(suffix);
         }
diff --git a/core/src/test/java/org/apache/shiro/realm/activedirectory/ActiveDirectoryRealmTest.java b/core/src/test/java/org/apache/shiro/realm/activedirectory/ActiveDirectoryRealmTest.java
index 727c541915..ce08f1e3af 100644
--- a/core/src/test/java/org/apache/shiro/realm/activedirectory/ActiveDirectoryRealmTest.java
+++ b/core/src/test/java/org/apache/shiro/realm/activedirectory/ActiveDirectoryRealmTest.java
@@ -130,6 +130,42 @@ public void testExistingUserSuffix() throws Exception {
         assertExistingUserSuffix(USERNAME + "@EXAMPLE.com", "testuser@EXAMPLE.com");
     }
 
+    /**
+     * Regression test for CVE-2026-49268 (LDAP injection): {@link ActiveDirectoryRealm} must escape
+     * user-supplied input per RFC 2253 before using it to build the LDAP query argument, so an
+     * attacker cannot inject extra RDN components / alter the query structure.
+     * <p/>
+     * Without the {@code Rdn.escapeValue(username)} fix the captured argument is the raw
+     * {@code testuser,ou=admins} (unescaped ',' and '=').
+     */
+    @Test
+    public void testGetRoleNamesForUserEscapesInjectionCharacters() throws Exception {
+
+        LdapContext ldapContext = createMock(LdapContext.class);
+        NamingEnumeration<SearchResult> results = createMock(NamingEnumeration.class);
+        Capture<Object[]> captureArgs = Capture.newInstance(CaptureType.ALL);
+        expect(ldapContext.search(anyString(), anyString(), capture(captureArgs), anyObject(SearchControls.class))).andReturn(results);
+        replay(ldapContext);
+
+        ActiveDirectoryRealm activeDirectoryRealm = new ActiveDirectoryRealm();
+
+        SecurityManager securityManager = new DefaultSecurityManager(activeDirectoryRealm);
+        Subject subject = new Subject.Builder(securityManager).buildSubject();
+        subject.execute(() -> {
+
+            try {
+                activeDirectoryRealm.getRoleNamesForUser("testuser,ou=admins", ldapContext);
+            } catch (NamingException e) {
+                Assert.fail("Unexpected NamingException thrown during test");
+            }
+        });
+
+        Object[] args = captureArgs.getValue();
+        assertThat(args, arrayWithSize(1));
+        // injected ',' and '=' are backslash-escaped, so they cannot break out of the value
+        assertThat(args[0], is("testuser\\,ou\\=admins"));
+    }
+
     public void assertExistingUserSuffix(String username, String expectedPrincipalName) throws Exception {
 
         LdapContext ldapContext = createMock(LdapContext.class);
diff --git a/core/src/test/java/org/apache/shiro/realm/ldap/DefaultLdapRealmTest.java b/core/src/test/java/org/apache/shiro/realm/ldap/DefaultLdapRealmTest.java
index a94927d798..cb4a448745 100644
--- a/core/src/test/java/org/apache/shiro/realm/ldap/DefaultLdapRealmTest.java
+++ b/core/src/test/java/org/apache/shiro/realm/ldap/DefaultLdapRealmTest.java
@@ -176,4 +176,33 @@ protected String getUserDnSuffix() {
         String userDn = realm.getUserDn(principal);
         assertEquals(principal, userDn);
     }
+
+    /**
+     * A normal username must be substituted into the template unchanged so that the fix for
+     * CVE-2026-49268 does not alter legitimate authentication behavior.
+     */
+    @Test
+    public void testGetUserDnLeavesOrdinaryUsernameUnchanged() {
+        realm.setUserDnTemplate("uid={0},ou=users,dc=mycompany,dc=com");
+        assertEquals("uid=jsmith,ou=users,dc=mycompany,dc=com", realm.getUserDn("jsmith"));
+    }
+
+    /**
+     * Regression test for CVE-2026-49268 (LDAP DN injection): user-supplied input must be escaped
+     * per RFC 2253 before being concatenated into the user DN, so an attacker cannot inject extra
+     * RDN components and alter the DN structure used for the bind.
+     * <p>
+     * Without the {@code Rdn.escapeValue(principal)} fix this returns
+     * {@code uid=jsmith,ou=admins,ou=users,dc=mycompany,dc=com} (two uid/ou breakouts).
+     */
+    @Test
+    public void testGetUserDnEscapesInjectionCharacters() {
+        realm.setUserDnTemplate("uid={0},ou=users,dc=mycompany,dc=com");
+
+        // Attacker attempts to break out of the uid RDN and graft on a privileged subtree.
+        String userDn = realm.getUserDn("jsmith,ou=admins");
+
+        // The injected ',' and '=' are backslash-escaped, leaving exactly one uid RDN intact.
+        assertEquals("uid=jsmith\\,ou\\=admins,ou=users,dc=mycompany,dc=com", userDn);
+    }
 }