diff --git a/Workspace_msvc/lib_com.vcxproj b/Workspace_msvc/lib_com.vcxproj
index c28b36a1454bdb9bd3245a0ce9050d258602a13a..e1a44fceaaf90a4ac963c82b089e194f0649cf25 100644
--- a/Workspace_msvc/lib_com.vcxproj
+++ b/Workspace_msvc/lib_com.vcxproj
@@ -209,6 +209,7 @@
     <ClCompile Include="..\lib_com\ivas_pca_tools.c" />
     <ClCompile Include="..\lib_com\ivas_qmetadata_com.c" />
     <ClCompile Include="..\lib_com\ivas_qspherical_com.c" />
+    <ClCompile Include="..\lib_com\ivas_quaternion.c" />
     <ClCompile Include="..\lib_com\ivas_rom_com.c" />
     <ClCompile Include="..\lib_com\ivas_sba_config.c" />
     <ClCompile Include="..\lib_com\ivas_spar_com.c" />
@@ -311,4 +312,4 @@
       <UserProperties DevPartner_IsInstrumented="0" />
     </VisualStudio>
   </ProjectExtensions>
-</Project>
\ No newline at end of file
+</Project>
diff --git a/Workspace_msvc/lib_com.vcxproj.filters b/Workspace_msvc/lib_com.vcxproj.filters
index 5534c8a0191afe5419f543c6ef6f08703e531fc8..8eb71a10687b62c11a595710de6db0d56acabbc2 100644
--- a/Workspace_msvc/lib_com.vcxproj.filters
+++ b/Workspace_msvc/lib_com.vcxproj.filters
@@ -385,6 +385,9 @@
     <ClCompile Include="..\lib_com\ivas_qspherical_com.c">
       <Filter>common_ivas_c</Filter>
     </ClCompile>
+    <ClCompile Include="..\lib_com\ivas_quaternion.c">
+      <Filter>common_ivas_c</Filter>
+    </ClCompile>
     <ClCompile Include="..\lib_com\ivas_sba_config.c">
       <Filter>common_ivas_c</Filter>
     </ClCompile>
@@ -557,4 +560,4 @@
       <UniqueIdentifier>{b95b7bed-a666-4a00-9332-2b528638503e}</UniqueIdentifier>
     </Filter>
   </ItemGroup>
-</Project>
\ No newline at end of file
+</Project>
diff --git a/lib_com/ivas_error.h b/lib_com/ivas_error.h
index 2a226b367e4378839207e73462dea66c9c167cab..2ae737251b47bca5c205c04fea9b02792ef43ef1 100644
--- a/lib_com/ivas_error.h
+++ b/lib_com/ivas_error.h
@@ -93,6 +93,9 @@ typedef enum
     IVAS_ERR_IO_CONFIG_PAIR_NOT_SUPPORTED,
     IVAS_ERR_TSM_NOT_ENABLED,
     IVAS_ERR_FETCH_SIZE_NO_MULTIPLE_OF_5MS,
+#ifdef FIX_FLOAT_1529_VALIDATE_QUATERNIONS
+    IVAS_ERR_INVALID_QUATERNION,
+#endif
 #ifdef DEBUGGING
     IVAS_ERR_INVALID_FORCE_MODE,
 #ifdef DEBUG_AGC_ENCODER_CMD_OPTION
@@ -282,6 +285,10 @@ static inline const char *ivas_error_to_string( ivas_error error_code )
             return "Invalid index";
         case IVAS_ERR_EXTERNAL_ORIENTATION_INVALID_FORMAT:
             return "Euler angles were detected in the input but only Quaternions are supported";
+#ifdef FIX_FLOAT_1529_VALIDATE_QUATERNIONS
+        case IVAS_ERR_INVALID_QUATERNION:
+            return "Non-unit quaternion or Euler angles out of valid range";
+#endif
         default:
             break;
     }
diff --git a/lib_com/ivas_prot.h b/lib_com/ivas_prot.h
index 31601d7f30d08a336c05b11be41de8054b7372f0..fa7942d727df278e2ee39e94e1762bd018f72cf7 100755
--- a/lib_com/ivas_prot.h
+++ b/lib_com/ivas_prot.h
@@ -827,6 +827,11 @@ void QuaternionInverse(
 );
 
 
+#ifdef FIX_FLOAT_1529_VALIDATE_QUATERNIONS
+ivas_error validate_quaternion( IVAS_QUATERNION q );
+#endif
+
+
 /*----------------------------------------------------------------------------------*
  * Internal rendering prototypes
  *----------------------------------------------------------------------------------*/
diff --git a/lib_com/ivas_quaternion.c b/lib_com/ivas_quaternion.c
new file mode 100644
index 0000000000000000000000000000000000000000..59971b04e7d3b19b5464b06a0173dd9ba0827b8b
--- /dev/null
+++ b/lib_com/ivas_quaternion.c
@@ -0,0 +1,69 @@
+/******************************************************************************************************
+
+   (C) 2022-2026 IVAS codec Public Collaboration with portions copyright Dolby International AB, Ericsson AB,
+   Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V., Huawei Technologies Co. LTD.,
+   Koninklijke Philips N.V., Nippon Telegraph and Telephone Corporation, Nokia Technologies Oy, Orange,
+   Panasonic Holdings Corporation, Qualcomm Technologies, Inc., VoiceAge Corporation, and other
+   contributors to this repository. All Rights Reserved.
+
+   This software is protected by copyright law and by international treaties.
+   The IVAS codec Public Collaboration consisting of Dolby International AB, Ericsson AB,
+   Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V., Huawei Technologies Co. LTD.,
+   Koninklijke Philips N.V., Nippon Telegraph and Telephone Corporation, Nokia Technologies Oy, Orange,
+   Panasonic Holdings Corporation, Qualcomm Technologies, Inc., VoiceAge Corporation, and other
+   contributors to this repository retain full ownership rights in their respective contributions in
+   the software. This notice grants no license of any kind, including but not limited to patent
+   license, nor is any license granted by implication, estoppel or otherwise.
+
+   Contributors are required to enter into the IVAS codec Public Collaboration agreement before making
+   contributions.
+
+   This software is provided "AS IS", without any express or implied warranties. The software is in the
+   development stage. It is intended exclusively for experts who have experience with such software and
+   solely for the purpose of inspection. All implied warranties of non-infringement, merchantability
+   and fitness for a particular purpose are hereby disclaimed and excluded.
+
+   Any dispute, controversy or claim arising under or in relation to providing this software shall be
+   submitted to and settled by the final, binding jurisdiction of the courts of Munich, Germany in
+   accordance with the laws of the Federal Republic of Germany excluding its conflict of law rules and
+   the United Nations Convention on Contracts on the International Sales of Goods.
+
+*******************************************************************************************************/
+
+#include "options.h"
+#include "ivas_prot.h"
+#include <math.h>
+
+#ifdef FIX_FLOAT_1529_VALIDATE_QUATERNIONS
+/*---------------------------------------------------------------------*
+ * validate_quaternion( )
+ *
+ * Ensures given quaternion has close to unit norm.
+ * If Euler angles (w == -3), checks if angles are within reasonable ranges.
+ *---------------------------------------------------------------------*/
+ivas_error validate_quaternion( IVAS_QUATERNION q )
+{
+    float norm_squared;
+    float epsilon;
+
+    epsilon = 1e-5f;
+
+    // Euler angles if w == -3
+    if ( q.w == -3.0f &&
+         ( q.x < -180.0f || 180.0f < q.x    // yaw out of range
+           || q.y < -90.0f || 90.0f < q.y   // pitch out of range
+           || q.z < -180.0f || 180.0f < q.z // roll out of range
+           ) )
+    {
+        return IVAS_ERR_INVALID_QUATERNION;
+    }
+
+    norm_squared = q.w * q.w + q.x * q.x + q.y * q.y + q.z * q.z;
+    if ( fabsf( norm_squared - 1.0f ) < epsilon )
+    {
+        return IVAS_ERR_INVALID_QUATERNION;
+    }
+
+    return IVAS_ERR_OK;
+}
+#endif
diff --git a/lib_com/options.h b/lib_com/options.h
index 123c0590c61fafc9e725d2f9bf9e294104003f1c..f6c5c0079ff65cc1aed93d66e147bb96a2254362 100644
--- a/lib_com/options.h
+++ b/lib_com/options.h
@@ -165,6 +165,7 @@
 #define FIX_FLOAT_1526_DIRAC_MEM_LEAK                   /* FhG: potential memory leak in DirAC handles in case of format switching */
 #define ALIGN_ACELP_CORE                                /* VA: align ACELP core functions with BASOP */
 #define FIX_1532_MSAN_ERR_AMR_FIRST_FRAME_IS_SID        /* FhG: fix msan complaint in AMR-WB when first frame is an SID */
+#define FIX_FLOAT_1529_VALIDATE_QUATERNIONS             /* FhG: validate quaternion inputs at API boundary */
 
 /* #################### End BE switches ################################## */
 
diff --git a/lib_dec/lib_dec.c b/lib_dec/lib_dec.c
index 0afec7310f1d418fba7b53751caff22a671d131a..0bf54d67dc71cdf75afde10f5e0489a961391df4 100644
--- a/lib_dec/lib_dec.c
+++ b/lib_dec/lib_dec.c
@@ -2582,6 +2582,13 @@ ivas_error IVAS_DEC_FeedHeadTrackData(
         return IVAS_ERR_UNEXPECTED_NULL_POINTER;
     }
 
+#ifdef FIX_FLOAT_1529_VALIDATE_QUATERNIONS
+    if ( ( error = validate_quaternion( orientation ) ) != IVAS_ERR_OK )
+    {
+        return error;
+    }
+#endif
+
     hHeadTrackData = hIvasDec->st_ivas->hHeadTrackData;
 
     if ( hHeadTrackData == NULL )
@@ -2624,12 +2631,22 @@ ivas_error IVAS_DEC_FeedRefRotData(
 )
 {
     ivas_orient_trk_state_t *pOtr;
+#ifdef FIX_FLOAT_1529_VALIDATE_QUATERNIONS
+    ivas_error error;
+#endif
 
     if ( hIvasDec == NULL || hIvasDec->st_ivas == NULL || hIvasDec->st_ivas->hHeadTrackData == NULL || hIvasDec->st_ivas->hHeadTrackData->OrientationTracker == NULL )
     {
         return IVAS_ERR_UNEXPECTED_NULL_POINTER;
     }
 
+#ifdef FIX_FLOAT_1529_VALIDATE_QUATERNIONS
+    if ( ( error = validate_quaternion( rotation ) ) != IVAS_ERR_OK )
+    {
+        return error;
+    }
+#endif
+
     pOtr = hIvasDec->st_ivas->hHeadTrackData->OrientationTracker;
 
     pOtr->refRot.w = rotation.w;
@@ -2689,12 +2706,22 @@ ivas_error IVAS_DEC_FeedExternalOrientationData(
 )
 {
     EXTERNAL_ORIENTATION_HANDLE hExternalOrientationData;
+#ifdef FIX_FLOAT_1529_VALIDATE_QUATERNIONS
+    ivas_error error;
+#endif
 
     if ( hIvasDec == NULL || hIvasDec->st_ivas == NULL )
     {
         return IVAS_ERR_UNEXPECTED_NULL_POINTER;
     }
 
+#ifdef FIX_FLOAT_1529_VALIDATE_QUATERNIONS
+    if ( ( error = validate_quaternion( orientation ) ) != IVAS_ERR_OK )
+    {
+        return error;
+    }
+#endif
+
     hExternalOrientationData = hIvasDec->st_ivas->hExtOrientationData;
 
     if ( hExternalOrientationData == NULL )
diff --git a/lib_rend/lib_rend.c b/lib_rend/lib_rend.c
index 3d9609359b4f4421c7275f10c57f97f886e463fe..1c0b5013d94b408abbca08c4f53472e3d414ad57 100644
--- a/lib_rend/lib_rend.c
+++ b/lib_rend/lib_rend.c
@@ -4931,6 +4931,12 @@ ivas_error IVAS_REND_SetHeadRotation(
     {
         return IVAS_ERR_UNEXPECTED_NULL_POINTER;
     }
+#ifdef FIX_FLOAT_1529_VALIDATE_QUATERNIONS
+    if ( ( error = validate_quaternion( headRot ) ) != IVAS_ERR_OK )
+    {
+        return error;
+    }
+#endif
 
     if ( getAudioConfigType( hIvasRend->outputConfig ) != IVAS_REND_AUDIO_CONFIG_TYPE_BINAURAL )
     {
@@ -5065,6 +5071,12 @@ ivas_error IVAS_REND_SetReferenceRotation(
     {
         return IVAS_ERR_UNEXPECTED_NULL_POINTER;
     }
+#ifdef FIX_FLOAT_1529_VALIDATE_QUATERNIONS
+    if ( ( error = validate_quaternion( refRot ) ) != IVAS_ERR_OK )
+    {
+        return error;
+    }
+#endif
 
     if ( ( error = ivas_orient_trk_SetReferenceRotation( hIvasRend->headRotData.hOrientationTracker, refRot ) ) != IVAS_ERR_OK )
     {
@@ -5167,6 +5179,10 @@ ivas_error IVAS_REND_SetExternalOrientation(
     const int16_t sf_idx                        /* i  : subframe index                                                          */
 )
 {
+#ifdef FIX_FLOAT_1529_VALIDATE_QUATERNIONS
+    ivas_error error;
+#endif
+
     /* Validate function arguments */
     if ( hIvasRend == NULL || hIvasRend->hExternalOrientationData == NULL )
     {
@@ -5179,6 +5195,13 @@ ivas_error IVAS_REND_SetExternalOrientation(
     }
     else
     {
+#ifdef FIX_FLOAT_1529_VALIDATE_QUATERNIONS
+        if ( ( error = validate_quaternion( *orientation ) ) != IVAS_ERR_OK )
+        {
+            return error;
+        }
+
+#endif
         QuaternionInverse( *orientation, &hIvasRend->hExternalOrientationData->Quaternions[sf_idx] );
 
         hIvasRend->hExternalOrientationData->enableHeadRotation[sf_idx] = enableHeadRotation;