diff --git a/tests/api/test_ed25519.c b/tests/api/test_ed25519.c
index 634cf47af2d..34d39099d33 100644
--- a/tests/api/test_ed25519.c
+++ b/tests/api/test_ed25519.c
@@ -169,6 +169,52 @@ int test_wc_ed25519_sign_msg(void)
 
 } /* END test_wc_ed25519_sign_msg */
 
+/*
+ * Test that wc_ed25519_sign_msg() rejects a public-key-only key object.
+ * A key with pubKeySet=1 but privKeySet=0 must not silently sign.
+ */
+int test_wc_ed25519_sign_msg_pubonly_fails(void)
+{
+    EXPECT_DECLS;
+#if !defined(HAVE_FIPS) || FIPS_VERSION3_GE(7,0,0)
+#if defined(HAVE_ED25519) && defined(HAVE_ED25519_SIGN) && \
+    defined(HAVE_ED25519_KEY_IMPORT) && defined(HAVE_ED25519_KEY_EXPORT)
+    ed25519_key fullKey;
+    ed25519_key pubOnlyKey;
+    WC_RNG      rng;
+    byte        pubBuf[ED25519_PUB_KEY_SIZE];
+    word32      pubSz = sizeof(pubBuf);
+    byte        msg[] = "test message for pubonly check";
+    byte        sig[ED25519_SIG_SIZE];
+    word32      sigLen = sizeof(sig);
+
+    XMEMSET(&fullKey, 0, sizeof(fullKey));
+    XMEMSET(&pubOnlyKey, 0, sizeof(pubOnlyKey));
+    XMEMSET(&rng, 0, sizeof(rng));
+
+    ExpectIntEQ(wc_ed25519_init(&fullKey), 0);
+    ExpectIntEQ(wc_ed25519_init(&pubOnlyKey), 0);
+    ExpectIntEQ(wc_InitRng(&rng), 0);
+
+    /* Generate a real key pair and export its public key. */
+    ExpectIntEQ(wc_ed25519_make_key(&rng, ED25519_KEY_SIZE, &fullKey), 0);
+    ExpectIntEQ(wc_ed25519_export_public(&fullKey, pubBuf, &pubSz), 0);
+
+    /* Import only the public key into a fresh key object. */
+    ExpectIntEQ(wc_ed25519_import_public(pubBuf, pubSz, &pubOnlyKey), 0);
+
+    /* Signing with a public-key-only object must fail. */
+    ExpectIntEQ(wc_ed25519_sign_msg(msg, sizeof(msg), sig, &sigLen,
+        &pubOnlyKey), WC_NO_ERR_TRACE(BAD_FUNC_ARG));
+
+    DoExpectIntEQ(wc_FreeRng(&rng), 0);
+    wc_ed25519_free(&pubOnlyKey);
+    wc_ed25519_free(&fullKey);
+#endif
+#endif
+    return EXPECT_RESULT();
+} /* END test_wc_ed25519_sign_msg_pubonly_fails */
+
 /*
  * Testing wc_ed25519_import_public()
  */
diff --git a/tests/api/test_ed25519.h b/tests/api/test_ed25519.h
index 81f71c30965..42b23ddda02 100644
--- a/tests/api/test_ed25519.h
+++ b/tests/api/test_ed25519.h
@@ -27,6 +27,7 @@
 int test_wc_ed25519_make_key(void);
 int test_wc_ed25519_init(void);
 int test_wc_ed25519_sign_msg(void);
+int test_wc_ed25519_sign_msg_pubonly_fails(void);
 int test_wc_ed25519_import_public(void);
 int test_wc_ed25519_import_private_key(void);
 int test_wc_ed25519_export(void);
@@ -40,6 +41,7 @@ int test_wc_Ed25519PrivateKeyToDer(void);
     TEST_DECL_GROUP("ed25519", test_wc_ed25519_make_key),           \
     TEST_DECL_GROUP("ed25519", test_wc_ed25519_init),               \
     TEST_DECL_GROUP("ed25519", test_wc_ed25519_sign_msg),           \
+    TEST_DECL_GROUP("ed25519", test_wc_ed25519_sign_msg_pubonly_fails), \
     TEST_DECL_GROUP("ed25519", test_wc_ed25519_import_public),      \
     TEST_DECL_GROUP("ed25519", test_wc_ed25519_import_private_key), \
     TEST_DECL_GROUP("ed25519", test_wc_ed25519_export),             \
diff --git a/tests/api/test_ed448.c b/tests/api/test_ed448.c
index f4f4bf5f50f..fd2b2393bc0 100644
--- a/tests/api/test_ed448.c
+++ b/tests/api/test_ed448.c
@@ -162,6 +162,52 @@ int test_wc_ed448_sign_msg(void)
     return EXPECT_RESULT();
 } /* END test_wc_ed448_sign_msg */
 
+/*
+ * Test that wc_ed448_sign_msg() rejects a public-key-only key object.
+ * A key with pubKeySet=1 but privKeySet=0 must not silently sign.
+ */
+int test_wc_ed448_sign_msg_pubonly_fails(void)
+{
+    EXPECT_DECLS;
+#if !defined(HAVE_FIPS) || FIPS_VERSION3_GE(7,0,0)
+#if defined(HAVE_ED448) && defined(HAVE_ED448_SIGN) && \
+    defined(HAVE_ED448_KEY_IMPORT) && defined(HAVE_ED448_KEY_EXPORT)
+    ed448_key fullKey;
+    ed448_key pubOnlyKey;
+    WC_RNG    rng;
+    byte      pubBuf[ED448_PUB_KEY_SIZE];
+    word32    pubSz = sizeof(pubBuf);
+    byte      msg[] = "test message for pubonly check";
+    byte      sig[ED448_SIG_SIZE];
+    word32    sigLen = sizeof(sig);
+
+    XMEMSET(&fullKey, 0, sizeof(fullKey));
+    XMEMSET(&pubOnlyKey, 0, sizeof(pubOnlyKey));
+    XMEMSET(&rng, 0, sizeof(rng));
+
+    ExpectIntEQ(wc_ed448_init(&fullKey), 0);
+    ExpectIntEQ(wc_ed448_init(&pubOnlyKey), 0);
+    ExpectIntEQ(wc_InitRng(&rng), 0);
+
+    /* Generate a real key pair and export its public key. */
+    ExpectIntEQ(wc_ed448_make_key(&rng, ED448_KEY_SIZE, &fullKey), 0);
+    ExpectIntEQ(wc_ed448_export_public(&fullKey, pubBuf, &pubSz), 0);
+
+    /* Import only the public key into a fresh key object. */
+    ExpectIntEQ(wc_ed448_import_public(pubBuf, pubSz, &pubOnlyKey), 0);
+
+    /* Signing with a public-key-only object must fail. */
+    ExpectIntEQ(wc_ed448_sign_msg(msg, sizeof(msg), sig, &sigLen,
+        &pubOnlyKey, NULL, 0), WC_NO_ERR_TRACE(BAD_FUNC_ARG));
+
+    DoExpectIntEQ(wc_FreeRng(&rng), 0);
+    wc_ed448_free(&pubOnlyKey);
+    wc_ed448_free(&fullKey);
+#endif
+#endif
+    return EXPECT_RESULT();
+} /* END test_wc_ed448_sign_msg_pubonly_fails */
+
 /*
  * Testing wc_ed448_import_public()
  */
diff --git a/tests/api/test_ed448.h b/tests/api/test_ed448.h
index 7b331fa6c00..f0dc2611724 100644
--- a/tests/api/test_ed448.h
+++ b/tests/api/test_ed448.h
@@ -27,6 +27,7 @@
 int test_wc_ed448_make_key(void);
 int test_wc_ed448_init(void);
 int test_wc_ed448_sign_msg(void);
+int test_wc_ed448_sign_msg_pubonly_fails(void);
 int test_wc_ed448_import_public(void);
 int test_wc_ed448_import_private_key(void);
 int test_wc_ed448_export(void);
@@ -40,6 +41,7 @@ int test_wc_Ed448PrivateKeyToDer(void);
     TEST_DECL_GROUP("ed448", test_wc_ed448_make_key),             \
     TEST_DECL_GROUP("ed448", test_wc_ed448_init),                 \
     TEST_DECL_GROUP("ed448", test_wc_ed448_sign_msg),             \
+    TEST_DECL_GROUP("ed448", test_wc_ed448_sign_msg_pubonly_fails), \
     TEST_DECL_GROUP("ed448", test_wc_ed448_import_public),        \
     TEST_DECL_GROUP("ed448", test_wc_ed448_import_private_key),   \
     TEST_DECL_GROUP("ed448", test_wc_ed448_export),               \
diff --git a/tests/api/test_mldsa.c b/tests/api/test_mldsa.c
index 2aa788e8615..8664ae58126 100644
--- a/tests/api/test_mldsa.c
+++ b/tests/api/test_mldsa.c
@@ -685,6 +685,84 @@ int test_wc_dilithium(void)
     return EXPECT_RESULT();
 }
 
+/*
+ * Test that wc_dilithium_sign_msg() rejects a public-key-only key object.
+ * A key with prvKeySet=0 must not silently sign with zeroed key data.
+ */
+int test_wc_dilithium_sign_pubonly_fails(void)
+{
+    EXPECT_DECLS;
+#if !defined(HAVE_FIPS) || FIPS_VERSION3_GE(7,0,0)
+#if defined(HAVE_DILITHIUM) && defined(WOLFSSL_WC_DILITHIUM) && \
+    !defined(WOLFSSL_DILITHIUM_NO_SIGN) && \
+    !defined(WOLFSSL_DILITHIUM_NO_MAKE_KEY) && \
+    !defined(WOLFSSL_DILITHIUM_NO_CTX)
+    dilithium_key* key;
+    dilithium_key* pubOnlyKey;
+    WC_RNG rng;
+    byte* pubBuf = NULL;
+    word32 pubLen = DILITHIUM_MAX_PUB_KEY_SIZE;
+    byte msg[] = "test message for pubonly check";
+    byte* sig = NULL;
+    word32 sigLen = DILITHIUM_MAX_SIG_SIZE;
+
+    key = (dilithium_key*)XMALLOC(sizeof(*key), NULL,
+        DYNAMIC_TYPE_TMP_BUFFER);
+    ExpectNotNull(key);
+    pubOnlyKey = (dilithium_key*)XMALLOC(sizeof(*pubOnlyKey), NULL,
+        DYNAMIC_TYPE_TMP_BUFFER);
+    ExpectNotNull(pubOnlyKey);
+    pubBuf = (byte*)XMALLOC(DILITHIUM_MAX_PUB_KEY_SIZE, NULL,
+        DYNAMIC_TYPE_TMP_BUFFER);
+    ExpectNotNull(pubBuf);
+    sig = (byte*)XMALLOC(DILITHIUM_MAX_SIG_SIZE, NULL,
+        DYNAMIC_TYPE_TMP_BUFFER);
+    ExpectNotNull(sig);
+
+    if (key != NULL)
+        XMEMSET(key, 0, sizeof(*key));
+    if (pubOnlyKey != NULL)
+        XMEMSET(pubOnlyKey, 0, sizeof(*pubOnlyKey));
+    XMEMSET(&rng, 0, sizeof(rng));
+
+    ExpectIntEQ(wc_InitRng(&rng), 0);
+    ExpectIntEQ(wc_dilithium_init(key), 0);
+    ExpectIntEQ(wc_dilithium_init(pubOnlyKey), 0);
+
+#ifndef WOLFSSL_NO_ML_DSA_44
+    ExpectIntEQ(wc_dilithium_set_level(key, WC_ML_DSA_44), 0);
+    ExpectIntEQ(wc_dilithium_set_level(pubOnlyKey, WC_ML_DSA_44), 0);
+#elif !defined(WOLFSSL_NO_ML_DSA_65)
+    ExpectIntEQ(wc_dilithium_set_level(key, WC_ML_DSA_65), 0);
+    ExpectIntEQ(wc_dilithium_set_level(pubOnlyKey, WC_ML_DSA_65), 0);
+#else
+    ExpectIntEQ(wc_dilithium_set_level(key, WC_ML_DSA_87), 0);
+    ExpectIntEQ(wc_dilithium_set_level(pubOnlyKey, WC_ML_DSA_87), 0);
+#endif
+
+    /* Generate a real key pair and export its public key. */
+    ExpectIntEQ(wc_dilithium_make_key(key, &rng), 0);
+    ExpectIntEQ(wc_dilithium_export_public(key, pubBuf, &pubLen), 0);
+
+    /* Import only the public key into a fresh key object. */
+    ExpectIntEQ(wc_dilithium_import_public(pubBuf, pubLen, pubOnlyKey), 0);
+
+    /* Signing with a public-key-only object must fail. */
+    ExpectIntEQ(wc_dilithium_sign_ctx_msg(NULL, 0, msg, sizeof(msg), sig,
+        &sigLen, pubOnlyKey, &rng), WC_NO_ERR_TRACE(BAD_FUNC_ARG));
+
+    DoExpectIntEQ(wc_FreeRng(&rng), 0);
+    wc_dilithium_free(pubOnlyKey);
+    wc_dilithium_free(key);
+    XFREE(sig, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    XFREE(pubBuf, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    XFREE(pubOnlyKey, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    XFREE(key, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+#endif
+#endif
+    return EXPECT_RESULT();
+} /* END test_wc_dilithium_sign_pubonly_fails */
+
 int test_wc_dilithium_make_key(void)
 {
     EXPECT_DECLS;
diff --git a/tests/api/test_mldsa.h b/tests/api/test_mldsa.h
index 2493100d0ab..92381c1812c 100644
--- a/tests/api/test_mldsa.h
+++ b/tests/api/test_mldsa.h
@@ -25,6 +25,7 @@
 #include <tests/api/api_decl.h>
 
 int test_wc_dilithium(void);
+int test_wc_dilithium_sign_pubonly_fails(void);
 int test_wc_dilithium_make_key(void);
 int test_wc_dilithium_sign(void);
 int test_wc_dilithium_verify(void);
@@ -42,6 +43,7 @@ int test_mldsa_pkcs12(void);
 
 #define TEST_MLDSA_DECLS                                                       \
     TEST_DECL_GROUP("mldsa", test_wc_dilithium),                               \
+    TEST_DECL_GROUP("mldsa", test_wc_dilithium_sign_pubonly_fails),           \
     TEST_DECL_GROUP("mldsa", test_wc_dilithium_make_key),                      \
     TEST_DECL_GROUP("mldsa", test_wc_dilithium_sign),                          \
     TEST_DECL_GROUP("mldsa", test_wc_dilithium_verify),                        \
diff --git a/tests/api/test_mlkem.c b/tests/api/test_mlkem.c
index c727194fbe1..e9e42661a2f 100644
--- a/tests/api/test_mlkem.c
+++ b/tests/api/test_mlkem.c
@@ -3872,3 +3872,81 @@ int test_wc_mlkem_decapsulate_kats(void)
     return EXPECT_RESULT();
 }
 
+/*
+ * Test that wc_MlKemKey_Decapsulate() rejects a public-key-only key object.
+ * A key with MLKEM_FLAG_PUB_SET but not MLKEM_FLAG_PRIV_SET must not
+ * silently decapsulate with zeroed private key data.
+ */
+int test_wc_mlkem_decapsulate_pubonly_fails(void)
+{
+    EXPECT_DECLS;
+#if !defined(HAVE_FIPS) || FIPS_VERSION3_GE(7,0,0)
+#if defined(WOLFSSL_HAVE_MLKEM) && defined(WOLFSSL_WC_MLKEM) && \
+    !defined(WOLFSSL_NO_ML_KEM) && !defined(WOLFSSL_MLKEM_NO_DECAPSULATE) && \
+    !defined(WOLFSSL_MLKEM_NO_ENCAPSULATE) && \
+    !defined(WOLFSSL_MLKEM_NO_MAKE_KEY)
+    MlKemKey* fullKey;
+    MlKemKey* pubOnlyKey;
+    WC_RNG rng;
+    byte ct[WC_ML_KEM_MAX_CIPHER_TEXT_SIZE];
+    byte ss[WC_ML_KEM_SS_SZ];
+    byte ssDec[WC_ML_KEM_SS_SZ];
+    byte pubBuf[WC_ML_KEM_MAX_PUBLIC_KEY_SIZE];
+    word32 pubLen = 0;
+    word32 ctLen = 0;
+
+    fullKey = (MlKemKey*)XMALLOC(sizeof(*fullKey), NULL,
+        DYNAMIC_TYPE_TMP_BUFFER);
+    ExpectNotNull(fullKey);
+    pubOnlyKey = (MlKemKey*)XMALLOC(sizeof(*pubOnlyKey), NULL,
+        DYNAMIC_TYPE_TMP_BUFFER);
+    ExpectNotNull(pubOnlyKey);
+
+    XMEMSET(&rng, 0, sizeof(rng));
+    ExpectIntEQ(wc_InitRng(&rng), 0);
+
+#ifndef WOLFSSL_NO_ML_KEM_768
+    ExpectIntEQ(wc_MlKemKey_Init(fullKey, WC_ML_KEM_768, NULL,
+        INVALID_DEVID), 0);
+    ExpectIntEQ(wc_MlKemKey_Init(pubOnlyKey, WC_ML_KEM_768, NULL,
+        INVALID_DEVID), 0);
+#elif !defined(WOLFSSL_NO_ML_KEM_512)
+    ExpectIntEQ(wc_MlKemKey_Init(fullKey, WC_ML_KEM_512, NULL,
+        INVALID_DEVID), 0);
+    ExpectIntEQ(wc_MlKemKey_Init(pubOnlyKey, WC_ML_KEM_512, NULL,
+        INVALID_DEVID), 0);
+#else
+    ExpectIntEQ(wc_MlKemKey_Init(fullKey, WC_ML_KEM_1024, NULL,
+        INVALID_DEVID), 0);
+    ExpectIntEQ(wc_MlKemKey_Init(pubOnlyKey, WC_ML_KEM_1024, NULL,
+        INVALID_DEVID), 0);
+#endif
+
+    /* Get correct sizes for this key type. */
+    ExpectIntEQ(wc_MlKemKey_PublicKeySize(fullKey, &pubLen), 0);
+    ExpectIntEQ(wc_MlKemKey_CipherTextSize(fullKey, &ctLen), 0);
+
+    /* Generate a real key pair. */
+    ExpectIntEQ(wc_MlKemKey_MakeKey(fullKey, &rng), 0);
+
+    /* Encapsulate with the full key to get a valid ciphertext. */
+    ExpectIntEQ(wc_MlKemKey_Encapsulate(fullKey, ct, ss, &rng), 0);
+
+    /* Export and import only the public key. */
+    ExpectIntEQ(wc_MlKemKey_EncodePublicKey(fullKey, pubBuf, pubLen), 0);
+    ExpectIntEQ(wc_MlKemKey_DecodePublicKey(pubOnlyKey, pubBuf, pubLen), 0);
+
+    /* Decapsulating with a public-key-only object must fail. */
+    ExpectIntEQ(wc_MlKemKey_Decapsulate(pubOnlyKey, ssDec, ct, ctLen),
+        WC_NO_ERR_TRACE(BAD_STATE_E));
+
+    DoExpectIntEQ(wc_FreeRng(&rng), 0);
+    wc_MlKemKey_Free(pubOnlyKey);
+    wc_MlKemKey_Free(fullKey);
+    XFREE(pubOnlyKey, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    XFREE(fullKey, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+#endif
+#endif
+    return EXPECT_RESULT();
+} /* END test_wc_mlkem_decapsulate_pubonly_fails */
+
diff --git a/tests/api/test_mlkem.h b/tests/api/test_mlkem.h
index 5b9e7bdf624..24c05d6a0cd 100644
--- a/tests/api/test_mlkem.h
+++ b/tests/api/test_mlkem.h
@@ -27,10 +27,12 @@
 int test_wc_mlkem_make_key_kats(void);
 int test_wc_mlkem_encapsulate_kats(void);
 int test_wc_mlkem_decapsulate_kats(void);
+int test_wc_mlkem_decapsulate_pubonly_fails(void);
 
 #define TEST_MLKEM_DECLS                                      \
     TEST_DECL_GROUP("mlkem", test_wc_mlkem_make_key_kats),    \
     TEST_DECL_GROUP("mlkem", test_wc_mlkem_encapsulate_kats), \
-    TEST_DECL_GROUP("mlkem", test_wc_mlkem_decapsulate_kats)
+    TEST_DECL_GROUP("mlkem", test_wc_mlkem_decapsulate_kats), \
+    TEST_DECL_GROUP("mlkem", test_wc_mlkem_decapsulate_pubonly_fails)
 
 #endif /* WOLFCRYPT_TEST_MLKEM_H */
diff --git a/wolfcrypt/src/dilithium.c b/wolfcrypt/src/dilithium.c
index 17a2dd8eb50..bc1deb42500 100644
--- a/wolfcrypt/src/dilithium.c
+++ b/wolfcrypt/src/dilithium.c
@@ -10192,6 +10192,9 @@ int wc_dilithium_sign_ctx_msg(const byte* ctx, byte ctxLen, const byte* msg,
     if ((ret == 0) && (ctx == NULL) && (ctxLen > 0)) {
         ret = BAD_FUNC_ARG;
     }
+    if ((ret == 0) && (!key->prvKeySet)) {
+        ret = BAD_FUNC_ARG;
+    }
 
 #ifdef WOLF_CRYPTO_CB
     if (ret == 0) {
diff --git a/wolfcrypt/src/ed25519.c b/wolfcrypt/src/ed25519.c
index 2e30d74899d..425531575b4 100644
--- a/wolfcrypt/src/ed25519.c
+++ b/wolfcrypt/src/ed25519.c
@@ -401,6 +401,8 @@ int wc_ed25519_sign_msg_ex(const byte* in, word32 inLen, byte* out,
 
     if (!key->pubKeySet)
         return BAD_FUNC_ARG;
+    if (!key->privKeySet)
+        return BAD_FUNC_ARG;
 
     /* check and set up out length */
     if (*outLen < ED25519_SIG_SIZE) {
diff --git a/wolfcrypt/src/ed448.c b/wolfcrypt/src/ed448.c
index b46d5f93f09..37674cad51d 100644
--- a/wolfcrypt/src/ed448.c
+++ b/wolfcrypt/src/ed448.c
@@ -367,6 +367,9 @@ int wc_ed448_sign_msg_ex(const byte* in, word32 inLen, byte* out,
     if ((ret == 0) && (!key->pubKeySet)) {
         ret = BAD_FUNC_ARG;
     }
+    if ((ret == 0) && (!key->privKeySet)) {
+        ret = BAD_FUNC_ARG;
+    }
 
     /* check and set up out length */
     if ((ret == 0) && (*outLen < ED448_SIG_SIZE)) {
diff --git a/wolfcrypt/src/wc_mlkem.c b/wolfcrypt/src/wc_mlkem.c
index 66c86e9f7b6..13944148b7a 100644
--- a/wolfcrypt/src/wc_mlkem.c
+++ b/wolfcrypt/src/wc_mlkem.c
@@ -1481,6 +1481,9 @@ int wc_MlKemKey_Decapsulate(MlKemKey* key, unsigned char* ss,
     if ((key == NULL) || (ss == NULL) || (ct == NULL)) {
         ret = BAD_FUNC_ARG;
     }
+    if ((ret == 0) && ((key->flags & MLKEM_FLAG_PRIV_SET) == 0)) {
+        ret = BAD_STATE_E;
+    }
 
     if (ret == 0) {
         /* Establish cipher text size based on key type. */