diff --git a/include/freerdp/codec/color.h b/include/freerdp/codec/color.h
index 79200bee1..c7e6cca3f 100644
--- a/include/freerdp/codec/color.h
+++ b/include/freerdp/codec/color.h
@@ -288,6 +288,7 @@ typedef struct gdi_palette gdiPalette;
 		return (FreeRDPGetBitsPerPixel(format) + 7) / 8;
 	}
 
+#if !defined(WITHOUT_FREERDP_3x_DEPRECATED)
 	/***
 	 *
 	 * @param width    width to copy in pixels
@@ -297,9 +298,27 @@ typedef struct gdi_palette gdiPalette;
 	 * @return          A buffer allocated with winpr_aligned_malloc(width * height, 16)
 	 *                  if successful, NULL otherwise.
 	 */
+
+	WINPR_DEPRECATED_VAR("[since 3.21.0] use freerdp_glyph_convert_ex instead",
+	                     WINPR_ATTR_MALLOC(winpr_aligned_free, 1)
+	                         FREERDP_API BYTE* freerdp_glyph_convert(
+	                             UINT32 width, UINT32 height, const BYTE* WINPR_RESTRICT data));
+#endif
+
+	/***
+	 *
+	 * @param width    width to copy in pixels
+	 * @param height   height to copy in pixels
+	 * @param data     source buffer, must be (nWidth + 7) / 8 bytes long
+	 * @param len      the length of \ref data in bytes
+	 *
+	 * @return          A buffer allocated with winpr_aligned_malloc(width * height, 16)
+	 *                  if successful, NULL otherwise.
+	 * @since version 3.21.0
+	 */
 	WINPR_ATTR_MALLOC(winpr_aligned_free, 1)
-	FREERDP_API BYTE* freerdp_glyph_convert(UINT32 width, UINT32 height,
-	                                        const BYTE* WINPR_RESTRICT data);
+	FREERDP_API BYTE* freerdp_glyph_convert_ex(UINT32 width, UINT32 height,
+	                                           const BYTE* WINPR_RESTRICT data, size_t len);
 
 	/***
 	 *
diff --git a/libfreerdp/codec/clear.c b/libfreerdp/codec/clear.c
index 0efa89f8d..f9aa4f000 100644
--- a/libfreerdp/codec/clear.c
+++ b/libfreerdp/codec/clear.c
@@ -1139,8 +1139,54 @@ INT32 clear_decompress(CLEAR_CONTEXT* WINPR_RESTRICT clear, const BYTE* WINPR_RE
 
 	if (glyphData)
 	{
-		const uint32_t w = MIN(nWidth, nDstWidth);
-		const uint32_t h = MIN(nHeight, nDstHeight);
+		uint32_t w = MIN(nWidth, nDstWidth);
+		if (nXDst > nDstWidth)
+		{
+			WLog_WARN(TAG, "glyphData copy area x exceeds destination: x=%" PRIu32 " > %" PRIu32,
+			          nXDst, nDstWidth);
+			w = 0;
+		}
+		else if (nXDst + w > nDstWidth)
+		{
+			WLog_WARN(TAG,
+			          "glyphData copy area x + width exceeds destination: x=%" PRIu32 " + %" PRIu32
+			          " > %" PRIu32,
+			          nXDst, w, nDstWidth);
+			w = nDstWidth - nXDst;
+		}
+
+		if (w != nWidth)
+		{
+			WLog_WARN(TAG,
+			          "glyphData copy area width truncated: requested=%" PRIu32
+			          ", truncated to %" PRIu32,
+			          nWidth, w);
+		}
+
+		uint32_t h = MIN(nHeight, nDstHeight);
+		if (nYDst > nDstHeight)
+		{
+			WLog_WARN(TAG, "glyphData copy area y exceeds destination: y=%" PRIu32 " > %" PRIu32,
+			          nYDst, nDstHeight);
+			h = 0;
+		}
+		else if (nYDst + h > nDstHeight)
+		{
+			WLog_WARN(TAG,
+			          "glyphData copy area y + height exceeds destination: x=%" PRIu32 " + %" PRIu32
+			          " > %" PRIu32,
+			          nYDst, h, nDstHeight);
+			h = nDstHeight - nYDst;
+		}
+
+		if (h != nHeight)
+		{
+			WLog_WARN(TAG,
+			          "glyphData copy area height truncated: requested=%" PRIu32
+			          ", truncated to %" PRIu32,
+			          nHeight, h);
+		}
+
 		if (!freerdp_image_copy_no_overlap(glyphData, clear->format, 0, 0, 0, w, h, pDstData,
 		                                   DstFormat, nDstStep, nXDst, nYDst, palette,
 		                                   FREERDP_KEEP_DST_ALPHA))
diff --git a/libfreerdp/codec/color.c b/libfreerdp/codec/color.c
index 2dd33ebc0..2659c92e6 100644
--- a/libfreerdp/codec/color.c
+++ b/libfreerdp/codec/color.c
@@ -242,14 +242,33 @@ fail:
 }
 #endif
 
+#if !defined(WITHOUT_FREERDP_3x_DEPRECATED)
 BYTE* freerdp_glyph_convert(UINT32 width, UINT32 height, const BYTE* WINPR_RESTRICT data)
+{
+	const size_t scanline = (width + 7ull) / 8ull;
+	const size_t required = scanline * height;
+	return freerdp_glyph_convert_ex(width, height, data, required);
+}
+#endif
+
+BYTE* freerdp_glyph_convert_ex(UINT32 width, UINT32 height, const BYTE* WINPR_RESTRICT data,
+                               size_t len)
 {
 	/*
 	 * converts a 1-bit-per-pixel glyph to a one-byte-per-pixel glyph:
 	 * this approach uses a little more memory, but provides faster
 	 * means of accessing individual pixels in blitting operations
 	 */
-	const UINT32 scanline = (width + 7) / 8;
+	const size_t scanline = (width + 7ull) / 8ull;
+	const size_t required = scanline * height;
+	if (len < required)
+		return NULL;
+
+	if ((len == 0) || (width == 0) || (height == 0))
+		return NULL;
+
+	WINPR_ASSERT(data);
+
 	BYTE* dstData = (BYTE*)winpr_aligned_malloc(1ull * width * height, 16);
 
 	if (!dstData)
diff --git a/libfreerdp/gdi/graphics.c b/libfreerdp/gdi/graphics.c
index 2f616148c..1521dbbaf 100644
--- a/libfreerdp/gdi/graphics.c
+++ b/libfreerdp/gdi/graphics.c
@@ -270,20 +270,17 @@ static BOOL gdi_Bitmap_SetSurface(rdpContext* context, rdpBitmap* bitmap, BOOL p
 /* Glyph Class */
 static BOOL gdi_Glyph_New(rdpContext* context, rdpGlyph* glyph)
 {
-	BYTE* data = NULL;
-	gdiGlyph* gdi_glyph = NULL;
-
 	if (!context || !glyph)
 		return FALSE;
 
-	gdi_glyph = (gdiGlyph*)glyph;
+	gdiGlyph* gdi_glyph = (gdiGlyph*)glyph;
 	gdi_glyph->hdc = gdi_GetDC();
 
 	if (!gdi_glyph->hdc)
 		return FALSE;
 
 	gdi_glyph->hdc->format = PIXEL_FORMAT_MONO;
-	data = freerdp_glyph_convert(glyph->cx, glyph->cy, glyph->aj);
+	BYTE* data = freerdp_glyph_convert_ex(glyph->cx, glyph->cy, glyph->aj, glyph->cb);
 
 	if (!data)
 	{