diff --git a/module/zfs/gzip.c b/module/zfs/gzip.c
index d183e998456..2dee3e1da78 100644
--- a/module/zfs/gzip.c
+++ b/module/zfs/gzip.c
@@ -96,13 +96,17 @@ zfs_gzip_decompress_buf(void *s_start, void *d_start, size_t s_len,
 	/* check if hardware accelerator can be used */
 	if (qat_dc_use_accel(d_len)) {
 		if (qat_compress(QAT_DECOMPRESS, s_start, s_len,
-		    d_start, d_len, &dstlen) == CPA_STATUS_SUCCESS)
-			return (0);
+		    d_start, d_len, &dstlen) == CPA_STATUS_SUCCESS) {
+			if ((size_t)dstlen == d_len)
+				return (0);
+		}
 		/* if hardware de-compress fail, do it again with software */
 	}
 
 	if (uncompress_func(d_start, &dstlen, s_start, s_len) != Z_OK)
 		return (-1);
+	if ((size_t)dstlen != d_len)
+		return (-1);
 
 	return (0);
 }
diff --git a/module/zfs/lz4_zfs.c b/module/zfs/lz4_zfs.c
index 0c03a6855c7..672b1bd27e6 100644
--- a/module/zfs/lz4_zfs.c
+++ b/module/zfs/lz4_zfs.c
@@ -88,17 +88,24 @@ zfs_lz4_decompress_buf(void *s_start, void *d_start, size_t s_len,
 	(void) n;
 	const char *src = s_start;
 	uint32_t bufsiz = BE_IN32(src);
+	int decoded;
 
 	/* invalid compressed buffer size encoded at start */
 	if (bufsiz + sizeof (bufsiz) > s_len)
 		return (1);
 
 	/*
-	 * Returns 0 on success (decompression function returned non-negative)
-	 * and non-zero on failure (decompression function returned negative).
+	 * LZ4_uncompress_unknownOutputSize returns the number of bytes decoded
+	 * on success, or a negative value on failure. An OpenZFS block must
+	 * expand to exactly d_len bytes
 	 */
-	return (LZ4_uncompress_unknownOutputSize(&src[sizeof (bufsiz)],
-	    d_start, bufsiz, d_len) < 0);
+	decoded = LZ4_uncompress_unknownOutputSize(&src[sizeof (bufsiz)],
+	    d_start, bufsiz, d_len);
+	if (decoded < 0)
+		return (1);
+	if (d_len != (size_t)decoded)
+		return (1);
+	return (0);
 }
 
 ZFS_COMPRESS_WRAP_DECL(zfs_lz4_compress)
diff --git a/module/zstd/zfs_zstd.c b/module/zstd/zfs_zstd.c
index 82212055f0e..f38800f7f34 100644
--- a/module/zstd/zfs_zstd.c
+++ b/module/zstd/zfs_zstd.c
@@ -682,6 +682,15 @@ zfs_zstd_decompress_level_buf(void *s_start, void *d_start, size_t s_len,
 		return (1);
 	}
 
+	/*
+	 * An OpenZFS compressed block must expand to exactly d_len bytes.
+	 * ZSTD_decompressDCtx returns the decompressed size on success.
+	 */
+	if (result != d_len) {
+		ZSTDSTAT_BUMP(zstd_stat_dec_fail);
+		return (1);
+	}
+
 	if (level) {
 		*level = curlevel;
 	}