diff --git a/packages/auth/providers/credentials/authorization/ldap-authorization.ts b/packages/auth/providers/credentials/authorization/ldap-authorization.ts
index 9f441aa9a..22dd15181 100644
--- a/packages/auth/providers/credentials/authorization/ldap-authorization.ts
+++ b/packages/auth/providers/credentials/authorization/ldap-authorization.ts
@@ -6,14 +6,14 @@ import type { Database, InferInsertModel } from "@homarr/db";
 import { and, eq } from "@homarr/db";
 import { users } from "@homarr/db/schema";
 import { logger } from "@homarr/log";
-import type { userSignInSchema } from "@homarr/validation/user";
+import type { ldapSignInSchema } from "@homarr/validation/user";
 
 import { env } from "../../../env";
 import { LdapClient } from "../ldap-client";
 
 export const authorizeWithLdapCredentialsAsync = async (
   db: Database,
-  credentials: z.infer<typeof userSignInSchema>,
+  credentials: z.infer<typeof ldapSignInSchema>,
 ) => {
   logger.info(`user ${credentials.name} is trying to log in using LDAP. Connecting to LDAP server...`);
   const client = new LdapClient();
@@ -38,7 +38,14 @@ export const authorizeWithLdapCredentialsAsync = async (
         attributes: [env.AUTH_LDAP_USERNAME_ATTRIBUTE, env.AUTH_LDAP_USER_MAIL_ATTRIBUTE],
       },
     })
-    .then((entries) => entries.at(0));
+    .then((entries) => {
+      if (entries.length > 1) {
+        logger.warn(`Multiple LDAP users found for ${credentials.name}, expected only one.`);
+        throw new CredentialsSignin();
+      }
+
+      return entries.at(0);
+    });
 
   if (!ldapUser) {
     logger.warn(`User ${credentials.name} not found in LDAP`);
diff --git a/packages/auth/providers/credentials/credentials-provider.ts b/packages/auth/providers/credentials/credentials-provider.ts
index 79e5eddf6..9de08da14 100644
--- a/packages/auth/providers/credentials/credentials-provider.ts
+++ b/packages/auth/providers/credentials/credentials-provider.ts
@@ -1,7 +1,7 @@
 import type Credentials from "@auth/core/providers/credentials";
 
 import type { Database } from "@homarr/db";
-import { userSignInSchema } from "@homarr/validation/user";
+import { ldapSignInSchema, userSignInSchema } from "@homarr/validation/user";
 
 import { authorizeWithBasicCredentialsAsync } from "./authorization/basic-authorization";
 import { authorizeWithLdapCredentialsAsync } from "./authorization/ldap-authorization";
@@ -28,7 +28,7 @@ export const createLdapConfiguration = (db: Database) =>
     name: "Ldap",
     // eslint-disable-next-line no-restricted-syntax
     async authorize(credentials) {
-      const data = await userSignInSchema.parseAsync(credentials);
+      const data = await ldapSignInSchema.parseAsync(credentials);
       return await authorizeWithLdapCredentialsAsync(db, data).catch(() => null);
     },
   }) satisfies CredentialsConfiguration;
diff --git a/packages/validation/src/user.ts b/packages/validation/src/user.ts
index 788eb2750..c00d9226d 100644
--- a/packages/validation/src/user.ts
+++ b/packages/validation/src/user.ts
@@ -69,6 +69,17 @@ export const userSignInSchema = z.object({
   password: z.string().min(1),
 });
 
+export const ldapSignInSchema = z.object({
+  name: z
+    .string()
+    .min(1)
+    // Prevent special characters that could lead to LDAP injection attacks
+    .regex(/^[^\\,+<>;"=)(*|!&]+$/, {
+      message: "Invalid characters in ldap username",
+    }),
+  password: z.string().min(1),
+});
+
 export const userRegistrationSchema = addConfirmPasswordRefinement(
   z.object({
     username: usernameSchema,